Paul,

Well that's a great clue!!!

After your confirmation that it should work for newly created documents, I noticed that the target .docm was in Compatibility Mode.

I started a new document, saved it as .docm and as .docx. Content Controls from the source .docm will paste into both of those as Content Controls (replicating your result). Although both of my original .docm documents were converted from .doc to .docm using the File Save procedure, the source document was not in Compatibility Mode; but, the target document was. I suspect the the Content Control Tool made the switch as being a requirement to create the Content Controls in the source document. I had not used the Content Control Tools add-in on the second .docm so it was content to remain in Compatibility mode.

It took some effort to find the options needing change to save the target .docm document without the save resulting in Compatibility Mode. When I finally figured that out, the pasting delivers the Content Control as intended. Interestingly, the Content Controls are not Mapped in the target document by default; but, I can handle that with Maxey's Content Control Tool and/or a macro that will run through all the Content Controls in a document.

For the record: The critical step in Word was File / Options / Advanced / Compatibility options for [filename], Lay out this document as if created in Microsoft Word 2013-2019.

Thanks for the help, Paul.

Thankfully,

Bruce Volkert
Currently undergoing withdrawal from Compatibility Mode