Strange, it works for me as it should. First pic after loading service from time table (with train line power on per default), second pic after switching train line power off in the loco. Third ... well. Maybe a specific service or journey mode?
there should be a keybind for coach lights, if not then... well, you're screwed. but look behind you, it might be on the board there
Couldn´t find any switch on the coach panels, like in the n-wagen for example. On a sarcastic side note: I couldn´t find any passengers either...
It seems that the lights are just rather dim, so that they don't really register in daytime. Contrast the 700, which is lit like an operating room!