Hi again David,
I may have found the answer but want to make sure with you. I have opened your ACT file and looked at it.
The image below shows at Dortmund (at bottom in PINK) the WB path for this activity. Just East of this area are located the BW Gleis 10 & 11 sidings you worked on.
At Dortmund, picking up cars at the BW Gleis 10 & 11 sidings requires the user to leave the WB path and venture outside the regular path to pick up the freight there. Leaving the regular path will require to turn manually the switches inside the area to exit and get back to your regular path. Here the only way to exit the area is by using the Dortmund BW Waschstrasse siding. The user must turn manually the switch and go beside one of the sidings just below, which seemed in direct line with the rail line when you left the area.
I am not sure if this is the answer but am giving a shot here. Let me know if there is something else I have missed here.
Thanks