I’ve just done some digging around in WP and ACF and it does not look to me that ACF (even though the problem goes away when you deactivate ACF) should be causing this, but I could be wrong.
Have you tried deactivating all of your other plugins to except ACF to see if you still get the errors? If you continue to get the error with only ACF active then submit a new ticket here https://support.advancedcustomfields.com/new-ticket/
