Hello, is that the same for you if you want to make your own scenario that you can do 20 train services but only 13 Train Services (AI)? Because if you want to do another train service, the buttons are locked to select any station, where the AI Train should start, except the Circle Button. I don't know if this is a bug and whether DTG has already investigated it.
I think I know what you mean. On SKA it's when you choose an AI service out of Düren I think. After you choose that particular platform in Düren, you can't add any other service. My suggestion is that you wait and create a service from this station and platform after you created the other. Hope I can help.
It is not only like this in Düren, it is everywhere on the entire route that you cannot select any train stations
