Steam Manchester Airport - Uncouple?

Timetable
5G40 Longsight Depot to Manchester Piccadilly (4:58)

this timetable will last 13 minutes, you are required to drive the train from the depot to Manchester Piccadilly platform 2, upon reaching Manchester Piccadilly you have to wait a couple of minutes before you are instructed to uncouple 3 vehicles (twice), however nothing I do is getting it to register that I am uncoupling the train even though it makes the uncouple sound, and you can even drive the train forward to create a gap clearly showing it’s been uncoupled.

I’ve now tried on two separate days and it’s not even a difficult thing to do you literally click one button which says “uncouple”

This is getting out of hand this was literally one of the very first timetable roots I did on this brand-new DLC and already a bug!

 

Has anyone done this route and had same issue or been able to complete it?