Try the following in order:
Run "%localappdata%\Microsoft\OneDrive\onedrive.exe /reset"
1. Open Word/Excel or Powerpoint and select Account (Or File > Account)
On the account screen, under User Information, sign out of all accounts . Please then close all MS Office Apps
2. Disconnect your Uni account from Start Menu > Settings > Accounts > Email and Accounts > Access work or school. Find your @uni account and click remove
3. Navigate to Start menu> Control panel> Credentials manager> Windows Credentials > delete all the saved university credentials.
Now restart your machine.
4. Navigate to
C:/ drive> Users> Username> AppData> Local> Microsoft> Office> Right click the folder and rename to Office.old
5. Once logged back in, open Word/Excel/Powerpoint application and sign-in with Microsoft credentials (uni email)
6.When prompted, it would be preferable for them to de-select 'allow you org to manage setting on this device' you must select 'This App Only'
Please now try opening/saving files to Onedrive again
Thanks to everyone on this thread https://answers.microsoft.com/en-us/msoffice/forum/msoffice_word-mso_win10-mso_o365b/microsoft-office-apps-stuck-in-processing-crashes/f915263f-9908-4966-8bbb-8b34bd736a07?page=3