At several of the S-Bahn stops on Koln-Aachen, Technologiepark the example right now, I am unable to board the S-Bahn train through the passenger doors. It appears to be too large of a step up, but no 'Press E to climb up' dialogue appears. The only way to remedy this is to sprint to the end and board a cab door.
Is there any way to fix this issue that you are facing by updating the route so that all the problems are removed?