Hi @Dan Wenzel
Welcome to our forum!
Where did you download Office 365?
What type of account is your account configured (POP/IMAP/Exchange)?
Please try the following solutions:
Please update your Outlook desktop client to the latest version.
Considering the impact of some add ins, it is suggested that you try to start outlook in safe mode (Win+R>type: outlook /safe) to check whether it works normally.
Considering that it would also be affected when the outlook program itself is damaged, it is recommended that you try to fix the Office application.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.