Just came across this while looking for another issue. I had a problem awhile back with a type of custom user on a WP site that wouldn’t show up in the Author dropdown box. It sounds unrelated, but the fix might help. After I applied some changes to the definition for that custom user type, the changes wouldn’t take place until I switched the user to another role (e.g., editor), then switched them back to the custom role I had defined. Doing that seemed to call the user definition function again, and the problem went away. If the problematic users are showing up in your Admin Panel->Users area, it might be worth a try.
On a side note, if you ever have 500 errors on your site, there is a severe conflict between the newer versions of WP Bakery Visual Composer and the All-in-one Event Calendar. Basically, you can’t use the shortcodes for the Timely Calendar in the content area, nor can you use the Timely widget(s) within Visual Composer without breaking that page (and possibly your site). You can put Timely stuff in a sidebar or call their shortcodes with PHP via a template or something.
