I faced this problem a year ago and can help you. All you need to do is to reset all the settings and clear cache. Don’t forget to do an Office 365 backup with the help of https://spinbackup.com/products/office-365-backup/ as a necessary precaution. It helped me, and I haven’t faced this problem ever since. Feel free to dm me.
I also faced the same problem with my office 365 I did not find the solution for the issue. I try to installed microsoft office 365 download from the official site and log in to the admin portal but it did not help me. if anyone know about this help me.