Upon opening a session, I issue a Drive to Trackmark command to a locomotive, which previously worked fine. However now the locomotive just sits there, and the bogeys or wheels disappear! I can't even move it manually. Now every time I start a session on that layout it does the same thing, with any locomotive and any trackmark. Even if I delete the session and start a new session with new rolling stock.
Any hints what it could be?
Any hints what it could be?