I hope my description is understandable (English is not my main language).
When you use the grouped/collapsed table names in the menu (it groups/collapses tables on double underscore by default) and you use (as example) the next three names:
This collapses in the menu into the group "event".
When you click on the group "event" in the menu, it does not show the table with the same name as the group (so here "event" has disappeared).
On our server we discovered this behavior with some user/user_ tables and it scared the living crp out of one of my developers. I tested it today on your demo server in the database "menagerie" and it happens there too.
I think this behavior is in PMA since the start of the new menu system.