Thanks for reporting. We will review the issue.
An error occurred while saving the commentJackie commented
We are having the same issue with InDesign 2021. Pages opening as read-only due to the fact that someone else is already in the page and if you don't know it's read-only and you make amendments it is only when you try to save the page you realise, it's very frustrating and could cause major errors. Please could you let us know how to solve this issue!