Apple Calendar client intermittently stops syncing with the Exchange server

I am having issues with a few users adding calendar appointments to their Outlook calendar in Apple Mail, but those appointments are not syncing to Microsoft's servers. This happens every few weeks after I manually delete the cache files from their computers - see this article for reference - not the same issue, but the same steps to fix:

https://michaelkummer.com/technology/fix-calendar-cant-save-event-x-exchange/

I have even completely removed and re-added the account (several times), but this only resolves the issue for a few weeks also. I'm wondering if anyone has a permanent fix for this issue. Having to remote into the President of your organization's computer monthly to bandage the issue doesn't look too good for the IT manager :/