diff --git a/custom_components/garmin_connect/coordinator.py b/custom_components/garmin_connect/coordinator.py
index 98d341c..8c929db 100644
--- a/custom_components/garmin_connect/coordinator.py
+++ b/custom_components/garmin_connect/coordinator.py
@@ -112,16 +112,40 @@ class GarminConnectDataUpdateCoordinator(DataUpdateCoordinator):
         hrv_status = {"status": "unknown"}
         endurance_data = {}
         endurance_status = {"overallScore": None}
+        hill_data = {}
+        hill_status = {"overallScore": None}
         menstrual_data = {}
         next_alarms: list[str] | None = []
 
         today = datetime.now(ZoneInfo(self.time_zone)).date()
+        current_hour = datetime.now(ZoneInfo(self.time_zone)).hour
+        yesterday_date = (today - timedelta(days=1)).isoformat()
+        _LOGGER.debug("Fetching data for date: %s (timezone: %s, hour: %s)", today.isoformat(), self.time_zone, current_hour)
 
         try:
             summary = await self.hass.async_add_executor_job(
                 self.api.get_user_summary, today.isoformat()
             )
 
+            # Midnight fallback: During 0:00-2:00 window, if today's data is empty/None,
+            # fallback to yesterday's data to avoid gaps due to UTC/GMT timezone differences
+            if current_hour < 2 and (not summary or summary.get("totalSteps") in (None, 0)):
+                _LOGGER.debug("Midnight fallback: Today's data empty, fetching yesterday's data")
+                yesterday_summary = await self.hass.async_add_executor_job(
+                    self.api.get_user_summary, yesterday_date
+                )
+                if yesterday_summary and yesterday_summary.get("totalSteps"):
+                    summary = yesterday_summary
+                    _LOGGER.debug("Using yesterday's summary data as fallback")
+
+            _LOGGER.debug(
+                "Summary data for %s: totalSteps=%s, dailyStepGoal=%s, lastSync=%s",
+                today.isoformat(),
+                summary.get("totalSteps"),
+                summary.get("dailyStepGoal"),
+                summary.get("lastSyncTimestampGMT"),
+            )
+
             # Fetch last 7 days steps for weekly average and yesterday's final count
             week_ago = (today - timedelta(days=7)).isoformat()
             yesterday = (today - timedelta(days=1)).isoformat()
@@ -191,6 +215,10 @@ class GarminConnectDataUpdateCoordinator(DataUpdateCoordinator):
                 self.api.get_endurance_score, today.isoformat()
             )
 
+            hill_data = await self.hass.async_add_executor_job(
+                self.api.get_hill_score, today.isoformat()
+            )
+
             try:
                 menstrual_data = await self.hass.async_add_executor_job(
                     self.api.get_menstrual_data_for_date, today.isoformat()
@@ -309,6 +337,12 @@ class GarminConnectDataUpdateCoordinator(DataUpdateCoordinator):
         except KeyError:
             pass
 
+        try:
+            if hill_data and "overallScore" in hill_data:
+                hill_status = hill_data
+        except KeyError:
+            pass
+
         return {
             **summary,
             **body["totalAverage"],
@@ -329,6 +363,7 @@ class GarminConnectDataUpdateCoordinator(DataUpdateCoordinator):
             "weeklyDistanceAvg": weekly_distance_avg,
             "hrvStatus": hrv_status,
             "enduranceScore": endurance_status,
+            "hillScore": hill_status,
             **fitnessage_data,
             **hydration_data,
             **menstrual_data,
diff --git a/custom_components/garmin_connect/quality_scale.yaml b/custom_components/garmin_connect/quality_scale.yaml
index aa2436a..6c3b728 100644
--- a/custom_components/garmin_connect/quality_scale.yaml
+++ b/custom_components/garmin_connect/quality_scale.yaml
@@ -27,7 +27,7 @@ rules:
   reconfiguration-flow: todo
   dynamic-devices: exempt  # Single cloud account, not device-based
   discovery: exempt  # Cloud service, not discoverable
-  diagnostics: todo
+  diagnostics: done
   exception-translations: todo
   icon-translations: todo
   stale-devices: exempt  # Single device per config entry
diff --git a/custom_components/garmin_connect/sensor.py b/custom_components/garmin_connect/sensor.py
index e2fd7f3..e1b0e53 100644
--- a/custom_components/garmin_connect/sensor.py
+++ b/custom_components/garmin_connect/sensor.py
@@ -4,7 +4,6 @@ from __future__ import annotations
 
 import datetime
 import logging
-from zoneinfo import ZoneInfo
 
 import voluptuous as vol
 from homeassistant.components.sensor import (
@@ -187,9 +186,17 @@ class GarminConnectSensor(GarminConnectEntity, SensorEntity, RestoreEntity):
         # Handle timestamp device class
         if self.entity_description.device_class == SensorDeviceClass.TIMESTAMP:
             if value:
-                value = datetime.datetime.fromisoformat(value).replace(
-                    tzinfo=ZoneInfo(self.coordinator.time_zone)
-                )
+                try:
+                    # Parse ISO format timestamp and set to UTC (GMT)
+                    parsed = datetime.datetime.fromisoformat(value)
+                    # If naive, assume UTC since Garmin returns GMT timestamps
+                    if parsed.tzinfo is None:
+                        value = parsed.replace(tzinfo=datetime.UTC)
+                    else:
+                        value = parsed
+                except (ValueError, TypeError):
+                    _LOGGER.debug("Could not parse timestamp: %s", value)
+                    value = None
 
         # Preserve int types, only round floats
         if isinstance(value, int):
diff --git a/custom_components/garmin_connect/sensor_descriptions.py b/custom_components/garmin_connect/sensor_descriptions.py
index 6ffae42..cc8bea1 100644
--- a/custom_components/garmin_connect/sensor_descriptions.py
+++ b/custom_components/garmin_connect/sensor_descriptions.py
@@ -11,6 +11,7 @@ from homeassistant.components.sensor import (
 )
 from homeassistant.const import (
     PERCENTAGE,
+    EntityCategory,
     UnitOfLength,
     UnitOfMass,
     UnitOfTime,
@@ -728,10 +729,19 @@ FITNESS_SENSORS: tuple[GarminConnectSensorEntityDescription, ...] = (
 
         value_fn=lambda data: data.get("enduranceScore", {}).get("overallScore"),
         attributes_fn=lambda data: {
-            "last_synced": data.get("lastSyncTimestampGMT"),
             **{k: v for k, v in data.get("enduranceScore", {}).items() if k != "overallScore"},
         },
     ),
+    GarminConnectSensorEntityDescription(
+        key="hillScore",
+        translation_key="hill_score",
+        state_class=SensorStateClass.MEASUREMENT,
+        icon="mdi:terrain",
+        value_fn=lambda data: data.get("hillScore", {}).get("overallScore"),
+        attributes_fn=lambda data: {
+            **{k: v for k, v in data.get("hillScore", {}).items() if k != "overallScore"},
+        },
+    ),
     GarminConnectSensorEntityDescription(
         key="physiqueRating",
         translation_key="physique_rating",
@@ -758,7 +768,7 @@ ACTIVITY_TRACKING_SENSORS: tuple[GarminConnectSensorEntityDescription, ...] = (
         icon="mdi:alarm",
         value_fn=lambda data: data.get("nextAlarm", [None])[0] if data.get("nextAlarm") else None,
         attributes_fn=lambda data: {
-            "last_synced": data.get("lastSyncTimestampGMT"),
+
             "next_alarms": data.get("nextAlarm"),
         },
     ),
@@ -769,7 +779,7 @@ ACTIVITY_TRACKING_SENSORS: tuple[GarminConnectSensorEntityDescription, ...] = (
 
         value_fn=lambda data: data.get("lastActivity", {}).get("activityName"),
         attributes_fn=lambda data: {
-            "last_synced": data.get("lastSyncTimestampGMT"),
+
             **data.get("lastActivity", {}),
         },
     ),
@@ -781,7 +791,7 @@ ACTIVITY_TRACKING_SENSORS: tuple[GarminConnectSensorEntityDescription, ...] = (
 
         value_fn=lambda data: len(data.get("lastActivities", [])),
         attributes_fn=lambda data: {
-            "last_synced": data.get("lastSyncTimestampGMT"),
+
             "last_activities": sorted(
                 data.get("lastActivities", []),
                 key=lambda x: x.get("activityId", 0),
@@ -796,7 +806,7 @@ ACTIVITY_TRACKING_SENSORS: tuple[GarminConnectSensorEntityDescription, ...] = (
 
         value_fn=lambda data: len(data.get("badges", [])),
         attributes_fn=lambda data: {
-            "last_synced": data.get("lastSyncTimestampGMT"),
+
             "badges": sorted(
                 data.get("badges", []),
                 key=lambda x: x.get("badgeEarnedDate", ""),
@@ -1012,7 +1022,7 @@ MENSTRUAL_CYCLE_SENSORS: tuple[GarminConnectSensorEntityDescription, ...] = (
         icon="mdi:calendar-heart",
         value_fn=lambda data: data.get("menstrualData", {}).get("currentPhase"),
         attributes_fn=lambda data: {
-            "last_synced": data.get("lastSyncTimestampGMT"),
+
             **{k: v for k, v in data.get("menstrualData", {}).items()
                if k not in ("currentPhase",)},
         },
@@ -1024,7 +1034,7 @@ MENSTRUAL_CYCLE_SENSORS: tuple[GarminConnectSensorEntityDescription, ...] = (
         state_class=SensorStateClass.MEASUREMENT,
         value_fn=lambda data: data.get("menstrualData", {}).get("dayOfCycle"),
         attributes_fn=lambda data: {
-            "last_synced": data.get("lastSyncTimestampGMT"),
+
         },
     ),
     GarminConnectSensorEntityDescription(
@@ -1034,7 +1044,7 @@ MENSTRUAL_CYCLE_SENSORS: tuple[GarminConnectSensorEntityDescription, ...] = (
         state_class=SensorStateClass.MEASUREMENT,
         value_fn=lambda data: data.get("menstrualData", {}).get("dayOfPeriod"),
         attributes_fn=lambda data: {
-            "last_synced": data.get("lastSyncTimestampGMT"),
+
         },
     ),
     GarminConnectSensorEntityDescription(
@@ -1045,7 +1055,7 @@ MENSTRUAL_CYCLE_SENSORS: tuple[GarminConnectSensorEntityDescription, ...] = (
         state_class=SensorStateClass.MEASUREMENT,
         value_fn=lambda data: data.get("menstrualData", {}).get("cycleLength"),
         attributes_fn=lambda data: {
-            "last_synced": data.get("lastSyncTimestampGMT"),
+
         },
     ),
     GarminConnectSensorEntityDescription(
@@ -1056,11 +1066,23 @@ MENSTRUAL_CYCLE_SENSORS: tuple[GarminConnectSensorEntityDescription, ...] = (
         state_class=SensorStateClass.MEASUREMENT,
         value_fn=lambda data: data.get("menstrualData", {}).get("periodLength"),
         attributes_fn=lambda data: {
-            "last_synced": data.get("lastSyncTimestampGMT"),
+
         },
     ),
 )
 
+# Diagnostic Sensors
+DIAGNOSTIC_SENSORS: tuple[GarminConnectSensorEntityDescription, ...] = (
+    GarminConnectSensorEntityDescription(
+        key="lastSyncTimestampGMT",
+        translation_key="last_synced",
+        device_class=SensorDeviceClass.TIMESTAMP,
+        entity_category=EntityCategory.DIAGNOSTIC,
+        icon="mdi:sync",
+        # Value is already an ISO timestamp string, just pass it through
+        value_fn=lambda data: data.get("lastSyncTimestampGMT"),
+    ),
+)
 
 ALL_SENSOR_DESCRIPTIONS: tuple[GarminConnectSensorEntityDescription, ...] = (
     *ACTIVITY_SENSORS,
@@ -1081,6 +1103,7 @@ ALL_SENSOR_DESCRIPTIONS: tuple[GarminConnectSensorEntityDescription, ...] = (
     *ADDITIONAL_DISTANCE_SENSORS,
     *WELLNESS_SENSORS,
     *MENSTRUAL_CYCLE_SENSORS,
+    *DIAGNOSTIC_SENSORS,
 )
 
 
diff --git a/custom_components/garmin_connect/strings.json b/custom_components/garmin_connect/strings.json
index 7bd97f9..fbb4543 100644
--- a/custom_components/garmin_connect/strings.json
+++ b/custom_components/garmin_connect/strings.json
@@ -33,24 +33,5 @@
       "already_configured": "[%key:common::config_flow::abort::already_configured_account%]",
       "reauth_successful": "[%key:common::config_flow::abort::reauth_successful%]"
     }
-  },
-  "entity": {
-    "sensor": {
-      "menstrual_cycle_phase": {
-        "name": "Menstrual cycle phase"
-      },
-      "menstrual_cycle_day": {
-        "name": "Menstrual cycle day"
-      },
-      "menstrual_period_day": {
-        "name": "Menstrual period day"
-      },
-      "menstrual_cycle_length": {
-        "name": "Menstrual cycle length"
-      },
-      "menstrual_period_length": {
-        "name": "Menstrual period length"
-      }
-    }
   }
 }
\ No newline at end of file
diff --git a/custom_components/garmin_connect/translations/en.json b/custom_components/garmin_connect/translations/en.json
index 13c6d7b..26ebd52 100644
--- a/custom_components/garmin_connect/translations/en.json
+++ b/custom_components/garmin_connect/translations/en.json
@@ -325,6 +325,9 @@
             "endurance_score": {
                 "name": "Endurance score"
             },
+            "hill_score": {
+                "name": "Hill score"
+            },
             "next_alarm": {
                 "name": "Next alarm"
             },
@@ -375,6 +378,9 @@
             },
             "menstrual_period_length": {
                 "name": "Menstrual period length"
+            },
+            "last_synced": {
+                "name": "Last synced"
             }
         }
     }
diff --git a/pyproject.toml b/pyproject.toml
index 5bc2c76..2823557 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ asyncio_mode = "auto"
 asyncio_default_fixture_loop_scope = "function"
 
 [tool.mypy]
-python_version = "3.11"
+python_version = "3.13"
 ignore_missing_imports = true
 check_untyped_defs = true
 warn_return_any = true
@@ -12,7 +12,7 @@ warn_unused_ignores = true
 show_error_codes = true
 
 [tool.ruff]
-target-version = "py311"
+target-version = "py313"
 line-length = 100
 
 [tool.ruff.lint]
diff --git a/requirements_lint.txt b/requirements_lint.txt
index 2a57457..f6a1791 100644
--- a/requirements_lint.txt
+++ b/requirements_lint.txt
@@ -12,5 +12,3 @@ ruff==0.14.10
 types-pytz==2025.2.0.20251108
 types-requests
 vulture==2.14
-
-