Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Could you update your OS to latest also? Usually latest OS and latest Office work good. Also try to update your Office so that if any patch is released by Microsoft that would flow in.
It is also possible that 16.9 version of Office has this bug as many issues are being reported in this new version.
Another option is roll back to previous stable version which you had. To rollback -
- Uninstall the latest version of Office - https://support.office.com/en-us/article/Uninst...
- Install the previous stable version - https://support.office.com/en-us/article/Update...
Optional - I would suggest that you should post simultaneously to Technet forum also as this will be looked into by MS Product team also. So, your question will be on two forums - This and Technet.