diff --git a/app/agenda/page.tsx b/app/agenda/page.tsx
index 4af70b3..b47ecc5 100644
--- a/app/agenda/page.tsx
+++ b/app/agenda/page.tsx
@@ -752,13 +752,27 @@ export default async function CalendarPage() {
   calendarsWithSync.forEach(cal => {
     const eventCount = cal.events?.length || 0;
     console.log(`[AGENDA] Calendar: ${cal.name}, provider: ${cal.syncConfig?.provider}, syncEnabled: ${cal.syncConfig?.syncEnabled}, hasMailCredential: ${!!cal.syncConfig?.mailCredential}, events: ${eventCount}`);
-    if (eventCount > 0 && cal.syncConfig?.provider === 'microsoft') {
-      console.log(`[AGENDA] Microsoft calendar events:`, cal.events.slice(0, 5).map(e => ({
+    if (cal.syncConfig?.provider === 'microsoft') {
+      // Log all Microsoft events with details
+      console.log(`[AGENDA] Microsoft calendar ${cal.id} events (${eventCount}):`, cal.events.map(e => ({
         id: e.id,
         title: e.title,
         start: e.start,
-        end: e.end
+        end: e.end,
+        isAllDay: e.isAllDay,
+        description: e.description ? e.description.substring(0, 50) : null
       })));
+      
+      // Also check directly in DB to see if there are more events
+      prisma.event.count({
+        where: { calendarId: cal.id }
+      }).then((dbCount) => {
+        if (dbCount !== eventCount) {
+          console.log(`[AGENDA] WARNING: Calendar ${cal.id} has ${eventCount} events in query but ${dbCount} in DB`);
+        }
+      }).catch((err) => {
+        console.error('[AGENDA] Error counting events in DB:', err);
+      });
     }
   });
 
diff --git a/lib/services/microsoft-calendar-sync.ts b/lib/services/microsoft-calendar-sync.ts
index e380c7f..e088bc8 100644
--- a/lib/services/microsoft-calendar-sync.ts
+++ b/lib/services/microsoft-calendar-sync.ts
@@ -138,20 +138,34 @@ export async function fetchMicrosoftEvents(
     };
 
     // Add date filter if provided
-    // Note: Microsoft Graph API filter for events needs to handle both timed and all-day events
-    // For all-day events, start/dateTime might not exist, so we use start/date instead
+    // Note: Microsoft Graph API filter syntax
+    // For timed events: start/dateTime
+    // For all-day events: start/date
+    // We need to handle both cases
     if (startDate && endDate) {
-      // Microsoft Graph API expects ISO format for date filters
-      // For all-day events, use start/date (YYYY-MM-DD format)
-      // For timed events, use start/dateTime (ISO format)
-      const startDateStr = startDate.toISOString().split('T')[0]; // YYYY-MM-DD
-      const endDateStr = endDate.toISOString().split('T')[0]; // YYYY-MM-DD
+      // Format dates for Microsoft Graph API
+      // For dateTime: ISO 8601 format (e.g., 2026-01-14T21:00:00Z)
+      // For date: YYYY-MM-DD format
+      const startDateStr = startDate.toISOString().split('T')[0];
+      const endDateStr = endDate.toISOString().split('T')[0];
       const startDateTimeStr = startDate.toISOString();
       const endDateTimeStr = endDate.toISOString();
       
-      // Filter: events where start is within range
-      // Handle both timed events (start/dateTime) and all-day events (start/date)
+      // Microsoft Graph API filter: match events where start is within range
+      // This handles both timed events (dateTime) and all-day events (date)
+      // The filter checks if either dateTime OR date is within range
       params.$filter = `(start/dateTime ge '${startDateTimeStr}' or start/date ge '${startDateStr}') and (start/dateTime le '${endDateTimeStr}' or start/date le '${endDateStr}')`;
+      
+      logger.debug('Microsoft Graph API filter', {
+        filter: params.$filter,
+        startDate: startDateStr,
+        endDate: endDateStr,
+        startDateTime: startDateTimeStr,
+        endDateTime: endDateTimeStr,
+      });
+    } else {
+      // If no date filter, get all events (might be too many, but useful for debugging)
+      logger.warn('No date filter provided, fetching all events (this might be slow)');
     }
     
     logger.debug('Fetching Microsoft events with params', {
@@ -178,12 +192,27 @@ export async function fetchMicrosoftEvents(
     });
 
     const events = response.data.value || [];
-    logger.debug('Microsoft Graph API response', {
+    logger.info('Microsoft Graph API response', {
       calendarId,
       eventCount: events.length,
       hasValue: !!response.data.value,
+      status: response.status,
+      // Log first few event IDs to verify they're being returned
+      eventIds: events.slice(0, 5).map(e => e.id),
     });
 
+    // Log if we got fewer events than expected
+    if (events.length === 0 && startDate && endDate) {
+      logger.warn('No events returned from Microsoft Graph API', {
+        calendarId,
+        dateRange: {
+          start: startDate.toISOString(),
+          end: endDate.toISOString(),
+        },
+        filter: params.$filter,
+      });
+    }
+
     return events;
   } catch (error) {
     logger.error('Error fetching Microsoft events', {
@@ -309,6 +338,7 @@ export async function syncMicrosoftCalendar(
       endDate
     );
 
+    // Log all events, not just first 10
     logger.info('Fetched Microsoft events', {
       calendarSyncId,
       eventCount: microsoftEvents.length,
@@ -316,7 +346,7 @@ export async function syncMicrosoftCalendar(
         start: startDate.toISOString(), 
         end: endDate.toISOString() 
       },
-      events: microsoftEvents.slice(0, 10).map(e => ({ 
+      allEvents: microsoftEvents.map(e => ({ 
         id: e.id, 
         subject: e.subject, 
         start: e.start.dateTime || e.start.date,
@@ -458,6 +488,11 @@ export async function syncMicrosoftCalendar(
       });
     }
 
+    // Verify events were actually saved to DB
+    const eventsInDb = await prisma.event.count({
+      where: { calendarId: syncConfig.calendarId }
+    });
+    
     logger.info('Microsoft calendar sync completed', {
       calendarSyncId,
       calendarId: syncConfig.calendarId,
@@ -466,6 +501,7 @@ export async function syncMicrosoftCalendar(
       created,
       updated,
       deleted,
+      eventsInDb,
     });
     
     // Log summary of created/updated events
@@ -475,6 +511,16 @@ export async function syncMicrosoftCalendar(
         newEventsCreated: created,
         eventsUpdated: updated,
         totalEventsInCalendar: caldavEvents.length,
+        eventsInDbAfterSync: eventsInDb,
+      });
+    }
+    
+    // Log warning if events count doesn't match
+    if (caldavEvents.length > 0 && eventsInDb === 0) {
+      logger.error('WARNING: Events were fetched but none were saved to DB', {
+        calendarSyncId,
+        fetchedCount: caldavEvents.length,
+        dbCount: eventsInDb,
       });
     }