I drove above mentioned service today. In this service the player continues a heavy freight service from Heigenbrucken to Gemunden after it was helped up the ramp by a banker loco. Service played out normally until 4 km out of Gemunden. I got stopped by a red signal. Looked on the map, saw several trains stacked up waiting to enter Gemunden. All trains were blocked a non moving train stuck on the entrance of Gemunden (see pic). Saved the game, turned off my PS4, and reloaded a few hours later. Sometimes that helps with stuck AI trians, but it didn't resolve the issue. Re-started the service. Went straight to the map. The stuck train was already there on the same spot.
The reason for this is the late start of service DB 88112. This should have left Gemünden two minutes earlier, but it wasn't set up in the right place when the game initiated the session. It should all work as expected when you spawn on foot at Heigenbrücken at 10:10 and take over service DB 83119 manually before 10:15.
Thanks for the advice. I just found another workaround though. I played DB83118 again (the service before this one, bringing it up the hill), and at the end I chose return to free roam, leading into DB83119. That also works
Yes, that's another possibility. You didn't start a new session, so the game didn't need to set up all other trains on the route.