
Hi,
It's possible that there may have been an update or change to the Teams or Excel online platform that is causing this issue. Here are a few suggestions from my side-
- Check if there are any updates available for Excel online or Teams. Updating to the latest version may resolve the issue.
- It's possible that there may have been a change to the settings accidentally or by another user. Maybe try checking once.
Try opening the workbook in a different web browser or clearing the cache and cookies in the current browser. Sometimes, browser issues can affect how Excel online works.
- Make sure that the users who are trying to format the cells have the necessary permissions. If they have been recently added to the team or their permissions have been changed, it's possible that they may not have the necessary access to format the cells.
Best Regards.