Error when appending a scan to pdf

Hello, I have a user who is getting the following error when trying to append a scan to a document that was printed to pdf.

"An error was encountered while running scanned image optimization. Aborting scanning operation" This only seems to happen when appending to 'print to pdf' files, it appends without issue to scanned pdfs.

Had this issue initially with Acrobat XI, uninstalled and replaced it with Acrobat 17. Worked correctly for a little while, now its giving the same error.