diff --git a/PKHeX.Core/Legality/Encounters/Generator/Search/EncounterEnumerator3.cs b/PKHeX.Core/Legality/Encounters/Generator/Search/EncounterEnumerator3.cs
index 6e375f042..e8e4e2adb 100644
--- a/PKHeX.Core/Legality/Encounters/Generator/Search/EncounterEnumerator3.cs
+++ b/PKHeX.Core/Legality/Encounters/Generator/Search/EncounterEnumerator3.cs
@@ -49,8 +49,8 @@ private enum YieldState : byte
         StartCaptures,
 
         SlotStart,
-        SlotR,
         SlotS,
+        SlotR,
         SlotE,
         SwarmRSE,
         SlotFR,
@@ -74,6 +74,7 @@ private enum YieldState : byte
 
     public bool MoveNext()
     {
+        top:
         switch (State)
         {
             case YieldState.Start:
@@ -145,33 +146,32 @@ public bool MoveNext()
             case YieldState.SlotStart:
                 if (!EncounterStateUtil.CanBeWildEncounter(Entity))
                     goto case YieldState.SlotEnd;
-                if (Version == GameVersion.R)
-                { State = YieldState.SlotR; goto case YieldState.SlotR; }
-                if (Version == GameVersion.S)
-                { State = YieldState.SlotS; goto case YieldState.SlotS; }
-                if (Version == GameVersion.E)
-                { State = YieldState.SlotE; goto case YieldState.SlotE; }
                 if (Version == GameVersion.FR)
                 { State = YieldState.SlotFR; goto case YieldState.SlotFR; }
                 if (Version == GameVersion.LG)
                 { State = YieldState.SlotLG; goto case YieldState.SlotLG; }
-                throw new ArgumentOutOfRangeException(nameof(Version));
+                if (Version is not (GameVersion.R or GameVersion.S or GameVersion.E))
+                    throw new ArgumentOutOfRangeException(nameof(Version));
+                State = YieldState.SwarmRSE; goto case YieldState.SwarmRSE;
+
+            case YieldState.SwarmRSE:
+                // Aggressively check for Swarm (special move), only one match possible. Next loop will reach regular slots.
+                // higher priority due to having special move, and poor vblank matching deferral tiebreaks
+                if (TryGetNext<EncounterArea3, EncounterSlot3>(Encounters3RSE.SlotsSwarmRSE))
+                    return true;
+                Index = 0; State = YieldState.SlotS + (byte)((byte)Version - 1); Index = 0; goto top;
 
             case YieldState.SlotR:
                 if (TryGetNext<EncounterArea3, EncounterSlot3>(Encounters3RSE.SlotsR))
                     return true;
-                Index = 0; State = YieldState.SwarmRSE; goto case YieldState.SwarmRSE;
+                Index = 0; goto case YieldState.SlotEnd;
             case YieldState.SlotS:
                 if (TryGetNext<EncounterArea3, EncounterSlot3>(Encounters3RSE.SlotsS))
                     return true;
-                Index = 0; State = YieldState.SwarmRSE; goto case YieldState.SwarmRSE;
+                Index = 0; goto case YieldState.SlotEnd;
             case YieldState.SlotE:
                 if (TryGetNext<EncounterArea3, EncounterSlot3>(Encounters3RSE.SlotsE))
                     return true;
-                Index = 0; State = YieldState.SwarmRSE; goto case YieldState.SwarmRSE;
-            case YieldState.SwarmRSE:
-                if (TryGetNext<EncounterArea3, EncounterSlot3>(Encounters3RSE.SlotsSwarmRSE))
-                    return true;
                 Index = 0; goto case YieldState.SlotEnd;
 
             case YieldState.SlotFR:
diff --git a/PKHeX.WinForms/Subforms/SaveHandlerTroubleshooter.cs b/PKHeX.WinForms/Subforms/SaveHandlerTroubleshooter.cs
index f4f5fbf41..f34c22644 100644
--- a/PKHeX.WinForms/Subforms/SaveHandlerTroubleshooter.cs
+++ b/PKHeX.WinForms/Subforms/SaveHandlerTroubleshooter.cs
@@ -37,8 +37,7 @@ private void InitializeBindings()
         var handlers = SaveUtil.Handlers.ToList();
         handlers.Insert(0, new SaveHandlerDefault());
         CB_Handler.DataSource = handlers
-            .Select(z => new HandlerItem(GetHandlerDisplayName(z), z))
-            .ToList();
+            .ConvertAll(z => new HandlerItem(GetHandlerDisplayName(z), z));
 
         UpdateSubVersionChoices();
     }
diff --git a/Tests/PKHeX.Core.Tests/Legality/Legal/Generation 3/Misc/0283 ★ - TEST - 5143F610D91A swarm lead matching.pk3 b/Tests/PKHeX.Core.Tests/Legality/Legal/Generation 3/Misc/0283 ★ - TEST - 5143F610D91A swarm lead matching.pk3
new file mode 100644
index 000000000..e0833b05f
Binary files /dev/null and b/Tests/PKHeX.Core.Tests/Legality/Legal/Generation 3/Misc/0283 ★ - TEST - 5143F610D91A swarm lead matching.pk3 differ