BATES Numbering, will my version work?

I am having trouble with Bates Numbering. The numbering is working fine. Numbers get added to my test run of 40 documents with the proper numbering, font, location etc. My problem is in the "Output Options" screen, trying to have the files automatically renamed, using either the %BATES_NUMBER_KEY% descriptor within "Add to original file names" option, or the "Replace file names with starting and ending Bates number..." option.

1. I've got "Adobe Acrobat Pro DC", Continuous Release | Version 2021.007.20091, as part of my DC subscription. Are these features supported in this version? The options certainly show up in the Output Options screen, so I would think these are available and supported. And, the Output Options *partially works* so it doesn't seem like a version issue.

2. Here's what does work:
I have a folder of 40 documents, and the Bates Numbers are added correctly into the documents.  I use "Add Folders". In "Output Options" I choose a "target folder" that is different than my source folder. I can choose "Keep original file names", which works. Or, I can add prefixes/suffixes in the "Add to original filenames" option, and add stuff like ABC_ and _XYZ, and it works. My output files are ABC_myfilename_XYZ.PDF.

3. Heres what does not work:
Add a prefix or suffix of %BATES_NUMBER_KEY%. For example, using %BATES_NUMBER_KEY% as "insert before", and _XYZ as "insert after", the numbering is fine, but the files are named myfilename_XYZ.PDF, rather than 00001-00005myfilename_XYZ.PDF like I would expect. I get no errors. Bates.log is empty

4. Here's what else doesn't work:

The "Replace file names with starting and ending Bates number..." option. For myfile.pdf, I would expect 00001-00005myfile.pdf as output. What happens instead is a message "The file may be read-only, or another user may have it open...". Nothing gets bates stamped, nothing appears in the output folder, and bates.log is empty.

I've tried using different filenames. This is all running on a local computer.

Any thoughts?