Why is Undo/Redo not working and disabled in Excel 2019 after autosaved code added

[ict_shiraz]

Hi guys ;
after adding code in below to my excel file found out undo / redo don't work.

Private Sub Workbook_BeforeClose(Cancel As Boolean)
Dim path As String
path = "c:\back\"
Application.DisplayAlerts = False
ThisWorkbook.Save
ThisWorkbook.SaveAs Filename:=path & Format(Now, "yyyymmdd@hhnnss"), FileFormat:=52
Application.DisplayAlerts = True
Application.Quit
End Sub

Why is Undo/Redo not working and disabled in Excel when auto save macro added and how to fix this issue in Excel 2019?

kindly advise