MU is the user role. All users with MU user role have access to these same content blocks.

“Is the same user logout/login to resolve a problem or on logout and other login?”
That is a VERY good question. I don’t know as I’m just requested to fix the problem.

So what can I do to try to resolve the issue? I’ve cleared out caching via WP Engine and the same issue occurs. I’m able to edit some but not all content blocks. The error is intermittent and doesn’t matter which content block I try to access.