OK, some additional information. I installed Admin Menu Editor to see what might be happening with this. Admin Menu Editor showed the menu as not visible. I then installed User Role Editor to see if there were missing permissions…and there are! In User Role Editor, if you turn on the deprecated options, you can see that none of the custom post type permissions are set. If you enable them, the menu appears.
I am having this issue and I do not have any plugins to manage or edit the menu or user roles installed. I can see that the custom post type was registered, but it does not show up in the admin menu (either the side nav or the bar). I did select the option to have it added.
