MS Office files on iCloud - suddenly cannot save or open

All of the sudden, overnight, I am unable to save or open any Microsoft Office files stored on iCloud that I have been using without issue on my MacBook Pro. I have signed out and signed back into Microsoft account, restarted my computer a dozen times, downloaded the files from iCloud.com and am able to open them locally, and copied the files from my iCloud drive to OneDrive and I'm able to open them there. I'm also able to open all other files saved on my iCloud drive. It's just Excel, Word, etc. files that I cannot open. I receive the below error messages. Any idea what the problem is and how I can fix it? I've seen others post about similar issues but cannot locate or determine any solution. Note: my Microsoft account is through my employer—not sure if this suddenly is an issue but our IT guy didn't seem to know anything about a change.