We got this issue 3 days ago, where one user can open but cannot choose save a file ( or select auto-save) from OneDrive Cloud using office desktop app (Excel). It will prompt with error lock file. The user has no issue modify the file using Excel for the Web. There is no issue with the Excel desktop app. Settings related to 'Trust' such as Protected View was not enabled. Repair/reinstall Office desktop app does not resolve the issue. Had the same issue when the same user using another computer. Other users were having similar issues now. My account is tenant admin and I do not have such issue.
