After an hour or so of testing, have tracked my problem, and it makes sense wrt what MasterTracklayer says above. I had copied a session and given new name to test an idea. basically was using THRoute paths instead of Enhanced Tower. I had not changed the Drive to or Drive Via commands to Autodrive to/through. It didn't like it, hence the skipping. Changing the Drive to Autodrive etc solved the issue. It can be inconsistent in the sense that previous Trainz versions sometimes allowed Drive via after THRoute or Path control - more recent 22+ seems unforgiving if you don't follow the rules! Thanks for the explanation MasterTracklayer.