Acrobat Pro DC Bug (version 21.007 using Windows 10)

This is a new bug, so suggests it relates to a recent update.

When Splitting a PDF file via Top Level Bookmark.
You receive the following error message (see screenshot).

"The file may be read-only, or another user may have it open. Please save the document with a different file name or in a different folder".

Trying either of the above suggestions will not work and you continue to receive the same error message when attempting to split the file.

The only way to get around this, is to manually select 'A Folder on My Computer' under the splitter Output Options menu. You can actually select the same folder which the original file is in and it works fine, which is odd as this is the same end result as the default selection (The Same Folder Selected at Start) which prompts the error message.

The error message appears with all my PDF files and colleagues, both desktop and server based. As mentioned it use to work fine so possible recent Acrobat Pro update bug.