Just finished 6M12 Redcar - Hatfield and it would not leave Tees Yard, I left the service after stopping and it wouldn't leave after I got the alight message. The objective market was over the last HEA when it said alight service.
I have also seen this when shunting in tees yard with the class 08, a 37 stopped at a red with a train from Redcar but it did eventually leave so I dont think it’s a bug it’s just programmed to stop for a while that’s all
I thought this too, and I was waiting for the next service, 6E19 to arrive into tees yard, however 6M12 was green lit down to eaglescliffe and there was a service to Saltburn held before Thornaby, and 6E19 held behind that, train didn't leave at all, I waited 30 minutes in the game until 13:10 and had to quit and load back in.
I’m pretty sure every service that you can drive to tees yard stops in the same place and eventually leaves