Was the synth track in sync BEFORE you added delay? If so, you'd need to look at the delay settings. Locking the track just stops it from being nudged by mistake but if you do this all you have to do is undo last action.
What interests me is how you were able to 1st of all play along with Audition to get the Reason track recorded and secondly HOW you recorded the Reason track. You or me could be missing something.