Dear Sarah Cornwell,
Good day.
Thank you for posting in Microsoft Community.
As per your mentioned query, seems like you have performed all the possible steps, but you are still facing this situation, in this given situation, your mentioned situation should be further checked by our technical support team from the backend side via collecting some detailed logs information, however, this is public forum, and we have limited access permission and resources, due to this reason, we cannot check certain type of detailed situation on forum community. But, our backend side technical support engineer will help you with more technical resources.
For this standard process, as Office 365 global admin may need to contact our technical support team via opening service request from admin center
Note: If your Office 365 Business standard / Premium / Enterprise subscription services are from reseller partner and as Office 365 global admin if you cannot open service request from your side, you may need to contact related reseller partner support provider to open service request on behalf of Office 365 global admin, after that Microsoft's technical support engineer will involve in service request.
I would really appreciate your precious time and kind cooperation.
Sincerely,
Darpan