Cannot mark Excel workbook as Final - vb.net

Question

The situation is as follows:
We want to publish to a remote machine a locally edited file. This file could be of type Word, Excel, Powerpoint. Apparently, after the publishing to the remote machine, we would like the local document to be marked as final, in order to prevent the user from editing it again (, because the intented workflow is first downloading it from the remote server, editing the downloaded document and the publishing it back to the server).
So, there is a bunch of code like this:
Public Sub setDocFinal()
Select Case addin.HostType
Case ADXOfficeHostApp.ohaWord
Dim doc As Word.Document = Nothing
Try
doc = addin.WordApp.ActiveDocument
doc.Final = True
Catch ex As Exception
Throw New Exception(Me.addin.getLabel("cannotSaveCopy", "Cannot Save the document."))
Finally
Marshal.ReleaseComObject(doc)
End Try
Case ADXOfficeHostApp.ohaExcel
Dim doc As Excel.Workbook = Nothing
Try
doc = addin.ExcelApp.ActiveWorkbook
doc.Final = True
'doc.RefreshAll()
'doc.CalculateUntilAsyncQueriesDone()
'doc.Calculate()
Catch ex As Exception
Throw New Exception(Me.addin.getLabel("cannotSaveCopy", "Cannot Save the document."))
Finally
Marshal.ReleaseComObject(doc)
End Try
' Powerpoint case intentionally skipped as is has same format/code
End Select
End Sub
The above code works pretty well for the Word case, but when it comes to Excel, it stacks on the popup which informs the user for the publish action to the remote server:
EDIT
At that particular point, the execution freezes (or maybe gets into an infinite internal loop, because the only available buttons in debugging mode are pause and stop) at the line of setting the document as final and it never reaches the finally statement (where we release the object). It also seems like the execution tries to return control back to the excel document, but nothing more than this notification occurs :
Any idea of what is wrong in the above code, regarding the handling of Excel?
The lines in comments display some trials I have been going through, while trying to find a solution around the net.
In addition, here is also the popup's related code:
Private Sub doWork(ByVal action As String, ByVal e As System.ComponentModel.DoWorkEventArgs)
Dim myDoc As MyDocument
myDoc = DirectCast(e.Argument, MyDocument)
System.Diagnostics.Debug.WriteLine("Post in Thread")
Dim resultObject(3) As Object
resultObject(0) = True
resultObject(1) = myDoc
Dim saveDocumentResult As SaveDocumentResult = Nothing
Try
Select Case action
Case Constants.SAVE_DRAFT
saveDocumentResult = myDoc.getRequestService().saveDraft(myDoc.getSaveFile(), myDoc.getDocName(), myDoc)
Case Constants.PUBLISH
saveDocumentResult = myDoc.getRequestService().publishDocument(myDoc.getSaveFile(), myDoc.getDocName(), myDoc)
myDoc.setDocFinal() 'this line makes the call to the above code
End Select
myDoc.updateDocumentProperty(Constants.VERSION, saveDocumentResult.version)
myDoc.updateDocumentProperty(Constants.HASH, saveDocumentResult.hash)
myDoc.setSaved(True)
System.Threading.Thread.Sleep(1500)
Catch ex As Exception
resultObject(0) = False
resultObject(2) = ex.Message
Finally
e.Result = resultObject
End Try
End Sub