Xbox Mp15dc Stuck At Red Light Extra 05-southbound Mow Part 2

Extra 05-Southbound MoW Part 2

A few minutes into the service, after picking up the first set and returning down and receiving the instruction to couple to the other 6, the light on the way to them is consistently red, contacting the dispatcher gets an instruction to proceed at restricted speed, but the light remains red consistently.
No reloads of saves, have restarted the service several times and it always happens.

 

An OK from the dispatcher means you can proceed without getting a SPAD, even when the light is still red. Isn't it?

 

It fails the scenario any time I go through it down the indicated track, alas.

This problem seems unique to this one service as it works as you describe on the other similar ones in this dlc.