White Box pop up when trying to password protect

Just like it says in the subject, when trying to password protect a document a blank white box pops up and it will not load any further. I can hit escape out of this box.

The work around has been to go into Advanced Options and Password Encrypt the document.

Version 21.007.2009 on a Windows 10 Pro

I have tried turning off "Show online storage when saving files" and turning off PDF/A view mode.

Thanks for your help