Office Automation, difference between 32 and 64 bit compile

I’m working on a transition to 64 bit (Windows, Xojo 21r2.1) of a major CMS-Project.

I just ran into a problem where generating a table in a word document results in an ole-exception on 64-bit. 32-bit works since a decade without problems. A hint where to look at is very appreciated, I did not find something helpful by now.

Here is the code-snippet:

// Tabelle erstellen
Word.ActiveDocument.Tables.Add(Word.Selection.Range, (PrbArr.ubound+2), 3, Office.wdWord9TableBehavior, Office.wdAutoFitFixed)
(!)Word.Selection.Tables(1).AutoFormat(Office.wdTableFormatNone, True, True, True, True, True, True, True, False, True)

(!)Word.Selection.Tables(1).cell(1, 1).Range.Text = "ProbID"
Word.Selection.Tables(1).cell(1, 2).Range.Text = "Empfänger / Proband"
Word.Selection.Tables(1).cell(1, 3).Range.Text = "IBAN"

OLE-Error okkurs on the (!) line, if the 1st is commented out then it throws an error on the second (!) line

Is the installed Office also 64 bit?

No, on my Testsystem it’s 32bit. It has to work on both Word 32 and 64.
32-bit Xojo App works for both.
Everything does his thing with Word/Excel when compiled with 64-bit, only creating/filling a table within word fails.