Can't flatten text boxes Adobe Acrobat Pro

I had an older version of Acrobat Pro until recently and I used to routinely flatten text boxes and stamps on my documents using pre-flight.  I am now running Acrobat Pro 2023.003.20269 and I can access the pre-flight tool and I found the "flatten transparency (high resolution, no decalibration of ICC based CMYK) function and run it and it seems to run OK but the text boxes are still listed as comments.  I also tried running the "flatterner preview" on all pages and same result.  How do I flatten comments in this newer version.  I found all kinds of help articles on how to do this for previous versions but they don't seem to apply to this version.