The problem is that in a UI Widget of type = World, the click event on a button does not work sometimes for some users.
When you are single player, it does not happen often; but it happens more often when there are even more players in the game.
It happens in my “Escape from the Museum” game, which uses a LockpadScript that is packaged.
But it also happens in the basic UI widget. The html button event is not triggered everytime. Once it works, it works, but it you leave and go back, a few times, it does not work. I am not able to reproduce it consistently, so I’m not sure how can I help.