Thanks for the good feedback.
You found a real bug. Thanks a lot. I confirm the case when these settings for post:
“Prohibit View – All visitors – Show access error message” returns 404 error instead of showing a globally set error message. I will re-test all options and publish the update in the 1st week of April.
I always get a 404 page from the active theme for ‘Return 404 HTTP error’ option although.
Show a screenshot of the settings you made for your post which produces unexpected result. I will test them with a double attention.