Xbox PC I Can’t Switch The Class 802 From Electric To Diesel Mode

I was trying to do the Class 802 test run service on Great Western Express, but once I get to where I have to switch to diesel mode, it won’t let me apply power. I followed the correct procedure; put it in neutral, lower the pantograph, hold the engine on button for 10 seconds, press the diesel mode button, and the engines do turn on, but when I apply power, the train doesn’t move. Am I doing anything wrong, or is this a known bug?

 

I have completed all jobs successfully with the 802 on xbox series x. You didn't put the holding brake on by accident did you.

 

Nope, the brakes are released. The train even rolls down the hill.

 

I got it to work by:
Power to off
Hold diesel mode
Start engines
Pantograph down
Reapply power.