I need help here. We have been using O365 Team Sites since September last year. I have a folder, in the documents library shared with our exec team. For the last 2 weeks, we have been experiencing issues with Excel spread-sheets opening in Read-only mode. All are on Windows 10 1709. All are using Office 365/2016. I need to resolve this issue.
Could you please provide more details about the issues you are having? If I understand you correctly, you are having problems with Excel files that are opened in read only mode...but: who is the user that is editing the file so other users get the read only experience?