diff --git a/.gitignore b/.gitignore
index 61446d20ed..a6b985d2fe 100644
--- a/.gitignore
+++ b/.gitignore
@@ -29,6 +29,7 @@ Bin/_setLatestBuildConfig.bat
 Bin/_setroot.bat
 Lib/debug/DebugProcs.lib
 Lib/debug/Generic.lib
+Lib/debug/System.ValueTuple.dll
 Lib/debug/unit++.*
 Lib/release/DebugProcs.lib
 Lib/release/Generic.lib
diff --git a/Src/Common/Controls/DetailControls/MSAReferenceComboBoxSlice.cs b/Src/Common/Controls/DetailControls/MSAReferenceComboBoxSlice.cs
index d0ae80edac..eefb2a0785 100644
--- a/Src/Common/Controls/DetailControls/MSAReferenceComboBoxSlice.cs
+++ b/Src/Common/Controls/DetailControls/MSAReferenceComboBoxSlice.cs
@@ -37,6 +37,7 @@ public class MSAReferenceComboBoxSlice : FieldSlice, IVwNotifyChange
 
 		//private bool m_processSelectionEvent = true;
 		private bool m_handlingMessage = false;
+		private bool m_forceRefresh = false;
 
 		/// ------------------------------------------------------------------------------------
 		/// <summary>
@@ -98,6 +99,8 @@ public override Mediator Mediator
 				m_MSAPopupTreeManager = new MSAPopupTreeManager(m_tree, m_cache, list,
 					m_tree.WritingSystemCode, true, m_mediator, m_propertyTable,
 					m_propertyTable.GetValue<Form>("window"));
+				m_MSAPopupTreeManager.BeforeChange += m_MSAPopupTreeManager_BeforeChange;
+				m_MSAPopupTreeManager.AfterChange += m_MSAPopupTreeManager_AfterChange;
 				m_MSAPopupTreeManager.AfterSelect += m_MSAPopupTreeManager_AfterSelect;
 				m_MSAPopupTreeManager.Sense = m_obj as ILexSense;
 				m_MSAPopupTreeManager.PersistenceProvider = m_persistProvider;
@@ -222,6 +225,33 @@ protected override void UpdateDisplayFromDatabase()
 			// What do we need to do here, if anything?
 		}
 
+		public void m_MSAPopupTreeManager_BeforeChange(object sender, TreeViewEventArgs e)
+		{
+			if (!ContainingDataTree.DoNotRefresh)
+			{
+				// Postpone refreshing the screen until m_MSAPopupTreeManager_AfterChange (LT-21980).
+				ContainingDataTree.DoNotRefresh = true;
+				m_forceRefresh = true;
+			}
+		}
+
+		public void m_MSAPopupTreeManager_AfterChange(object sender, TreeViewEventArgs e)
+		{
+			if (m_forceRefresh)
+			{
+				m_forceRefresh = false;
+				// We can't call RefreshDataTree directly,
+				// since that will cause Windows to crash accessing a disposed object.
+				// So, we queue it on the UI thread instead.
+				this.BeginInvoke(new Action(RefreshDataTree));
+			}
+		}
+
+		public void RefreshDataTree()
+		{
+			ContainingDataTree.DoNotRefresh = false;
+		}
+
 		private void m_MSAPopupTreeManager_AfterSelect(object sender, TreeViewEventArgs e)
 		{
 			// unless we get a mouse click or simulated mouse click (e.g. by ENTER or TAB),
@@ -286,7 +316,9 @@ private void m_MSAPopupTreeManager_AfterSelect(object sender, TreeViewEventArgs
 				// We still can't refresh the data at this point without causing a crash due to
 				// a pending Windows message.  See LT-9713 and LT-9714.
 				if (ContainingDataTree.DoNotRefresh != fOldDoNotRefresh)
+				{
 					Mediator.BroadcastMessage("DelayedRefreshList", fOldDoNotRefresh);
+				}
 			}
 		}
 
diff --git a/Src/LexText/LexTextControls/MSAPopupTreeManager.cs b/Src/LexText/LexTextControls/MSAPopupTreeManager.cs
index b294d55807..4ed27add30 100644
--- a/Src/LexText/LexTextControls/MSAPopupTreeManager.cs
+++ b/Src/LexText/LexTextControls/MSAPopupTreeManager.cs
@@ -44,6 +44,9 @@ public class MSAPopupTreeManager : PopupTreeManager
 
 		#region Events
 
+		public event TreeViewEventHandler BeforeChange;
+		public event TreeViewEventHandler AfterChange;
+
 		#endregion Events
 
 		/// <summary>
@@ -419,11 +422,19 @@ private bool EditExistingMsa()
 					m_sense.MorphoSyntaxAnalysisRA.Hvo, true, m_sEditGramFunc);
 				if (dlg.ShowDialog(ParentForm) == DialogResult.OK)
 				{
+					if (BeforeChange != null)
+					{
+						BeforeChange(this, null);
+					}
 					Cache.DomainDataByFlid.BeginUndoTask(String.Format(LexTextControls.ksUndoSetX, FieldName),
 						String.Format(LexTextControls.ksRedoSetX, FieldName));
 					m_sense.SandboxMSA = dlg.SandboxMSA;
 					Cache.DomainDataByFlid.EndUndoTask();
 					LoadPopupTree(m_sense.MorphoSyntaxAnalysisRA.Hvo);
+					if (AfterChange != null)
+					{
+						AfterChange(this, null);
+					}
 					return true;
 				}
 			}