Don't think this is a bug but worth noting it anyway Even when pressing Y or U unless the train is powered (master key in and on) and the unit in some form of drive (so reverser set) the doors won't open, presumably because the controls don't know which way right and left are until this is set
Interesting information. You should specify the train you drive. Maybe it is not the case for all of them. I am aware that in some trains the doors do not open until the train is fully booted. Did you check with the old menu, if that is working?
That is the case for a long time for all trains, door operations only work once the reverser is set. If that is prototypical or not, no clue, but that has always been the case
I checked the Javelin, 31/101 combo and the 465 and I think it was the same on the old method, but posted this in case someone went "My buttons aren't working!" without checking such things first