diff --git a/osu.Game/Database/RealmObjectExtensions.cs b/osu.Game/Database/RealmObjectExtensions.cs
index a771aa04df..5a6c2e3232 100644
--- a/osu.Game/Database/RealmObjectExtensions.cs
+++ b/osu.Game/Database/RealmObjectExtensions.cs
@@ -3,10 +3,12 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Runtime.Serialization;
 using AutoMapper;
 using AutoMapper.Internal;
+using osu.Framework.Logging;
 using osu.Game.Beatmaps;
 using osu.Game.Input.Bindings;
 using osu.Game.Models;
@@ -52,10 +54,23 @@ namespace osu.Game.Database
              {
                  foreach (var beatmap in s.Beatmaps)
                  {
-                     var existing = d.Beatmaps.FirstOrDefault(b => b.ID == beatmap.ID);
+                     // Importantly, search all of realm for the beatmap (not just the set's beatmaps).
+                     // It may have gotten detached, and if that's the case let's use this opportunity to fix
+                     // things up.
+                     var existingBeatmap = d.Realm.Find<BeatmapInfo>(beatmap.ID);
 
-                     if (existing != null)
-                         copyChangesToRealm(beatmap, existing);
+                     if (existingBeatmap != null)
+                     {
+                         // As above, reattach if it happens to not be in the set's beatmaps.
+                         if (!d.Beatmaps.Contains(existingBeatmap))
+                         {
+                             Debug.Fail("Beatmaps should never become detached under normal circumstances. If this ever triggers, it should be investigated further.");
+                             Logger.Log("WARNING: One of the difficulties in a beatmap was detached from its set. Please save a copy of logs and report this to devs.", LoggingTarget.Database, LogLevel.Important);
+                             d.Beatmaps.Add(existingBeatmap);
+                         }
+
+                         copyChangesToRealm(beatmap, existingBeatmap);
+                     }
                      else
                      {
                          var newBeatmap = new BeatmapInfo
@@ -64,6 +79,7 @@ namespace osu.Game.Database
                              BeatmapSet = d,
                              Ruleset = d.Realm.Find<RulesetInfo>(beatmap.Ruleset.ShortName)
                          };
+
                          d.Beatmaps.Add(newBeatmap);
                          copyChangesToRealm(beatmap, newBeatmap);
                      }