PowerPoint Add-In Loss of RibbonUI

Question

I have been struggling to identify the cause of an error in a PPT Add-in that is distributed across about 40 end users.

Problem: loss of the ribbon st

Answer 1

Found the real solution: Credit

    Public Declare Sub CopyMemory Lib "kernel32" Alias _
    "RtlMoveMemory" (destination As Any, source As Any, _
    ByVal length As Long)

Public Sub ribbon L o a ded(ribbon As IRibbonUI)
   ' Store pointer to IRibbonUI
   Dim lngRibPtr As Long
' Store the custom ribbon UI Id in a static variable.
' This is done once during load of UI. I.e. during workbook open.
    Set guiRibbon = ribbon
    lngRibPtr = ObjPtr(ribbon)
    ' Write pointer to worksheet for safe keeping
    Tabelle2.Range("A1").Value = lngRibPtr
End Sub
Function GetRibbon(lngRibPtr as Long) As Object
   Dim objRibbon As Object
   CopyMemory objRibbon, lngRibPtr, 4
   Set GetRibbon = objRibbon
   ' clean up invalid object
   CopyMemory objRibbon, 0&, 4
   Set objRibbon = Nothing
End Function

Then

    Public Sub DoButton(ByVal control As IRibbonControl)
' The onAction callback for btn1 and btn2

    ' Toggle state
    Toggle12 = Not Toggle12

    ' Invalidate the ribbon UI so that the enabled-states get reloaded
    If Not (guiRibbon Is Nothing) Then
        ' Invalidate will force the UI to reload and thereby ask for their enabled-states
        guiRibbon.Invalidate 'Control ("tabCustom") InvalidateControl does not work reliably
    Else
      Set guiRibbon = GetRibbon(CLng(Tabelle2.Range("A1").Value))
      guiRibbon.Invalidate
        ' The static guiRibbon-variable was meanwhile lost
'        MsgBox "Due to a design flaw in the architecture of the MS ribbon UI you have to close " & _
'            "and reopen this workbook." & vbNewLine & vbNewLine & _
'            "Very sorry about that.", vbExclamation + vbOKOnly
      MsgBox "Hopefully this is sorted now?"
        ' Note: In the help we can find
        ' guiRibbon.Refresh
        ' but unfortunately this is not implemented.
        ' It is exactly what we should have instead of that brute force reload mechanism.
    End If

End Sub