More fixes.

src/Squidex.Infrastructure.MongoDb/EventSourcing/StreamPosition.cs

@@ -11,7 +11,7 @@ namespace Squidex.Infrastructure.EventSourcing
 {
     internal sealed class StreamPosition
     {
-        private static readonly BsonTimestamp EmptyTimestamp = new BsonTimestamp(0);
+        private static readonly BsonTimestamp EmptyTimestamp = new BsonTimestamp(946681200, 0);
 
         public BsonTimestamp Timestamp { get; }
 

src/Squidex.Infrastructure.MongoDb/UsageTracking/MongoUsageRepository.cs

@@ -76,7 +76,6 @@ namespace Squidex.Infrastructure.UsageTracking
             var id = $"{usageUpdate.Key}_{usageUpdate.Date:yyyy-MM-dd}_{usageUpdate.Category}";
 
             var update = Update
-                .SetOnInsert(x => x.Id, id)
                 .SetOnInsert(x => x.Key, usageUpdate.Key)
                 .SetOnInsert(x => x.Date, usageUpdate.Date)
                 .SetOnInsert(x => x.Category, usageUpdate.Category);