I have had lots of issues with this stupid Microsoft Upload Center. I kept getting this error message
“The Microsoft Office Document Cache encountered a problem”. I would click to repair, but then I got this error message “This action cannot be completed because another application is using the Microsoft Office Document Cache”.
So on and so on, nothing worked. The I found this link
Now unfortunately it didn’t fix my particular problem, but it did tell me what was wrong, and advised on a reinstall of O365 if I couldn’t fix it. I did the reinstall and now all is good.
Maybe this will help you some day too.