A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data
Dear Peter,
Thanks for writing back and updating us.
I agree with the inconvenience caused because of the experimenting the troubleshooting steps but I am sorry to convey that the root cause of the problem can be determined with the help of the logs while reproducing the problem. However, the moderators in this community are limited with the resources to collect the logs and investigate it further, where you need to connect with the Microsoft Phone support team to find the root cause of the problem. Reference: Get support - Microsoft 365 admin | Microsoft Learn
However, as you mentioned the problem doesn’t happen in the Safe Mode, here is the reference article where it explains what Safe Mode do: Use safe mode on your Mac - Apple Support
So, you can try to restart your Mac device in the normal mode and see whether the same problem happens. If no problem happens, then the cause of the issue is resolved by the action performed by Safe Mode:
Appreciate your patience with us and have a great day!!
Best Regards,
Sophia