Hi @Don Walker ,
I noticed that you did a system upgrade, so I recommend that you repair Office from the Control Panel.
If your Outlook profile is corrupted or damaged, it can also be the reason behind the issue. It is recommended you create a new profile and re-connect your Gmail account to see if it works.
Check if google send you an email urging you to review your security settings. If so, change your Gmail account settings to allow "Less Secure Apps" may solve the problem.
If your issue has any update, please feel free to post back.
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.