workbook_open stopped working

[MLExcel]

<!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--> Hello everybody,


I recently run into a problem with workbook_open.

The code has been successfully running for years.
Now if I open the file nothing happens. Or almost always nothing happens. Sometimes (rarely) it does still work. Unfortunately I cannot reproduce it.

I believe the problem started when I experimented with EnableEvents=True/False in another procedure.

Any help is highly appreciated.
M.



Here is the code:

  Private Sub Workbook_Open()
  Call Sichern
  End Sub
   


  Sub Sichern()
   
      Application.Calculate
   
      antwort = MsgBox("Backup?", vbYesNo, "Backup?")
      If antwort = vbYes Then
   
      'Speichern unter Backup-Dateinamen
      ThisFile = Range("Backup_Pfad").Value

      ActiveWorkbook.SaveAs FileName:=ThisFile, ReadOnlyRecommended:=True
   
      'Speichern unter altem Dateinamen
          'Dabei wird die Datei überschrieben
          'Damit keine Eingabeaufforderung erscheint werden die Alerts ausgeschalten
      Application.DisplayAlerts = False
      ThisFile = Range("Dateipfad").Value

      ActiveWorkbook.SaveAs FileName:=ThisFile, ReadOnlyRecommended:=False
        
      Application.DisplayAlerts = True
      MsgBox "Backup saved!", vbOKOnly
      
      End If
   

  End Sub

There are no other macros in the workbook!
The Sub Sichern itself is working.

The Range("Backup_Pfad") and Range("Dateipfad") refer to cells within the workbook that contain (actually calculate) the filename and location.

Here is a link to the file:
https://1drv.ms/x/s!AlTXI0a7_oHihtNjzUUJzLk5wklAxw

 

[MLExcel]

Excel 2016
Office 365 ProPlus
Version 1701 (Build 7766.2099)

windows 10 Pro 64 bit