Update this morning:
Out of the 11 posts that the user role should be able to edit, only two were able to be edited (even though all 11 are listed).

The first one I was able to make edits/save/re-edit/resave without issue.
The second one I was able to make edits/save/re-edit and I attempted to save only to be presented with the message: Sorry, you are not allowed to edit this post.

Then when I attempted to edit any of the others, the error message appeared intermittently.