Renaming a folder that contains a Read-only asset from the Sources Panel causes the Content Browser and Sources Panel to desync. This causes the original folder (which should still exist since the Editor cannot replace the name of the folder due to the Read-only asset) to disappear from the Sources Panel and become unable to be opened in the Content Browser.
This can be worked around by either renaming the folder in the Content Browser instead or restarting the editor after the desync occurs.
Regression?: No
This occurred in 4.20
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-68647 in the post.