After having completed the 05:32 ICE619 service to München Hbf on Hauptstrecke München Augsburg which selected from timetable mode, I pressed continue journey. The service I was continuing to was an S3 service to Holzkirchen (the third one in chapter 3). Instead of a BR 423 spawning in at Mammendorf, an ICE train spawned in for me to drive the service. I then went back to the main menu and continued my journey to drive the S3 service and a BR423 spawned in as it should have.