I have setup a 3D widget, and I put widget interaction in my controller. If I start the game with only 1 player, I can receive the clicks in the widget (although I have to double click instead the first time).
Thanks! Using the OnPressed event instead of the OnClicked event worked for me. So strange that I had to use that workaround though. OnClicked worked perfectly fine in single player and in multiplayer I can even see the click animation on the button on the widget, yet the event isn’t called.