When playing the Early Morning Service scenario on the Mildmay Line, I’m having trouble after the initial movement where upon changing ends and following the scenario instructions to change to DC power and change the points, the train doesn’t move. I’ve tried all the variations I can and nothing works. The only solution is for me to switch it back to the original AC, power the train to pick up speed before the train moves off the overhead power lines. After a brief period of testing, only once the train is fully past the points and on the lines the Bakerloo line trains run on will the power work in DC mode.
I had the same issue (PC steam). It seems the timing of the instructions on when to switch power modes are not correct.
I had the same issue as well on the PS5. Took me a couple of attempts of switching to DC that it finally worked. This was while I was sat in the platform at Willesden Junction low level
I'm perhaps a little late, but my findings may help someone else like me who was struggling. At the start, when asked to change to DC, just press the button and releases; DON'T hold the button until it becomes lit. You should find that the train starts moving. so follow the instructions and stop as requested. After changing ends again, you'll probably find that the train won't move, again. This time, press and HOLD the DC button until it does light then you should find the train will now move.