Also migrate IsFolder

Jellyfin.Server/Migrations/Routines/MigrateLibraryDb.cs

@@ -105,7 +105,7 @@ internal class MigrateLibraryDb : IDatabaseMigrationRoutine
             Audio, ExternalServiceId, IsInMixedFolder, DateLastSaved, LockedFields, Studios, Tags, TrailerTypes, OriginalTitle, PrimaryVersionId,
             DateLastMediaAdded, Album, LUFS, NormalizationGain, CriticRating, IsVirtualItem, SeriesName, UserDataKey, SeasonName, SeasonId, SeriesId,
             PresentationUniqueKey, InheritedParentalRatingValue, ExternalSeriesId, Tagline, ProviderIds, Images, ProductionLocations, ExtraIds, TotalBitrate,
-            ExtraType, Artists, AlbumArtists, ExternalId, SeriesPresentationUniqueKey, ShowId, OwnerId, MediaType, SortName, CleanName, UnratedType FROM TypedBaseItems
+            ExtraType, Artists, AlbumArtists, ExternalId, SeriesPresentationUniqueKey, ShowId, OwnerId, MediaType, SortName, CleanName, UnratedType, IsFolder FROM TypedBaseItems
             """;
             using (new TrackedMigrationStep("Loading TypedBaseItems", _logger))
             {
@@ -1167,6 +1167,11 @@ internal class MigrateLibraryDb : IDatabaseMigrationRoutine
             entity.UnratedType = unratedType;
         }
 
+        if (reader.TryGetBoolean(index++, out var isFolder))
+        {
+            entity.IsFolder = isFolder;
+        }
+
         var baseItem = BaseItemRepository.DeserializeBaseItem(entity, _logger, null, false);
         var dataKeys = baseItem.GetUserDataKeys();
         userDataKeys.AddRange(dataKeys);