Provide BeatmapItemsCount in all filters to ensure we always use correct value

osu.Game/Graphics/Carousel/ICarouselFilter.cs

@@ -19,5 +19,10 @@ namespace osu.Game.Graphics.Carousel
         /// <param name="cancellationToken">A cancellation token.</param>
         /// <returns>The post-filtered items.</returns>
         Task<List<CarouselItem>> Run(IEnumerable<CarouselItem> items, CancellationToken cancellationToken);
+
+        /// <summary>
+        /// The total number of beatmap difficulties displayed post filter.
+        /// </summary>
+        int BeatmapItemsCount { get; }
     }
 }

osu.Game/Screens/SelectV2/BeatmapCarousel.cs

@@ -54,7 +54,7 @@ namespace osu.Game.Screens.SelectV2
         /// <summary>
         /// Total number of beatmap difficulties displayed with the filter.
         /// </summary>
-        public int MatchedBeatmapsCount => grouping.BeatmapItemsCount;
+        public int MatchedBeatmapsCount => Filters.Last().BeatmapItemsCount;
 
         protected override float GetSpacingBetweenPanels(CarouselItem top, CarouselItem bottom)
         {

osu.Game/Screens/SelectV2/BeatmapCarouselFilterMatching.cs

@@ -17,9 +17,6 @@ namespace osu.Game.Screens.SelectV2
     {
         private readonly Func<FilterCriteria> getCriteria;
 
-        /// <summary>
-        /// The total number of beatmap difficulties displayed post filter.
-        /// </summary>
         public int BeatmapItemsCount { get; private set; }
 
         public BeatmapCarouselFilterMatching(Func<FilterCriteria> getCriteria)

osu.Game/Screens/SelectV2/BeatmapCarouselFilterSorting.cs

@@ -16,6 +16,8 @@ namespace osu.Game.Screens.SelectV2
 {
     public class BeatmapCarouselFilterSorting : ICarouselFilter
     {
+        public int BeatmapItemsCount { get; private set; }
+
         private readonly Func<FilterCriteria> getCriteria;
 
         public BeatmapCarouselFilterSorting(Func<FilterCriteria> getCriteria)
@@ -29,6 +31,8 @@ namespace osu.Game.Screens.SelectV2
 
             bool groupedSets = BeatmapCarouselFilterGrouping.ShouldGroupBeatmapsTogether(criteria);
 
+            BeatmapItemsCount = items.Count();
+
             return items.Order(Comparer<CarouselItem>.Create((a, b) =>
             {
                 var ab = (BeatmapInfo)a.Model;