Unable to edit posts on discussion topics

Hi, I suddenly encountered the issue of being unable to edit posts that I previously made. 

Each time I try to save an edit to an earlier post, I keep getting the error "Access denied". This happens to all my posts on multiple discussion topics. I have tried to log out and log back in multiple times on different browsers but the issue still remains. I have no issue creating new posts.

Can you please advise what the cause is and how to resolve the issue? Thank you very much for your help.

Update: The issue has been resolved.