Realm-timing-related test failures

gistfile1.txt

osu.Game.Tests.Visual.Multiplayer.TestSceneMultiplayer.TestGameplayFlow
osu.Game.Tests.Visual.Multiplayer.TestSceneMultiplayer.TestItemAddedAndDeletedByOtherUserDuringGameplay
osu.Game.Tests.Visual.Multiplayer.TestSceneMultiplayer.TestItemAddedByOtherUserDuringGameplay
osu.Game.Tests.Visual.Multiplayer.TestSceneMultiplayer.TestPlayStartsWithCorrectBeatmapWhileAtSongSelect
osu.Game.Tests.Visual.Multiplayer.TestSceneMultiplayer.TestPlayStartsWithCorrectModsWhileAtSongSelect
osu.Game.Tests.Visual.Multiplayer.TestSceneMultiplayer.TestPlayStartsWithCorrectRulesetWhileAtSongSelect
osu.Game.Tests.Visual.Multiplayer.TestSceneMultiplayer.TestSpectatingStateNotResetOnBackButtonOutsideOfGameplay
osu.Game.Tests.Visual.Multiplayer.TestSceneMultiplayer.TestSpectatingStateResetOnBackButtonDuringGameplay
osu.Game.Tests.Visual.Multiplayer.TestSceneMultiplayer.TestUserSetToIdleWhenBeatmapDeleted
osu.Game.Tests.Visual.Playlists.TestScenePlaylistsRoomCreation.TestLoadSimpleMatch
osu.Game.Tests.Visual.Playlists.TestScenePlaylistsRoomCreation.TestPlaylistItemSelectedOnCreate
osu.Game.Tests.Visual.SongSelect.TestSceneTopLocalRank.TestHigherScoreSet

repro.patch

diff --git a/osu.Game/Database/RealmObjectExtensions.cs b/osu.Game/Database/RealmObjectExtensions.cs
index 6dc18df9e0..a956e451d0 100644
--- a/osu.Game/Database/RealmObjectExtensions.cs
+++ b/osu.Game/Database/RealmObjectExtensions.cs
@@ -5,6 +5,8 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Runtime.Serialization;
+using System.Threading;
+using System.Threading.Tasks;
 using AutoMapper;
 using AutoMapper.Internal;
 using osu.Game.Beatmaps;
@@ -279,7 +281,16 @@ public static Live<T> ToLive<T>(this T realmObject, RealmAccess realm)
             if (!RealmAccess.CurrentThreadSubscriptionsAllowed)
                 throw new InvalidOperationException($"Make sure to call {nameof(RealmAccess)}.{nameof(RealmAccess.RegisterForNotifications)}");

-            return collection.SubscribeForNotifications(callback);
+            return collection.SubscribeForNotifications((a, b, c) =>
+            {
+                SynchronizationContext ctx = SynchronizationContext.Current;
+
+                Task.Run(async () =>
+                {
+                    await Task.Delay(2000).ConfigureAwait(false);
+                    ctx.Post(_ => callback(a, b, c), null);
+                });
+            });
         }

         /// <summary>