No need for all these posts at the various forums. Can't have a look at the track right now. But I did have the same issue until I learned to do it the correct way. When I got my original TM Cougar, I was confused. I also thought pressing that button on the TQS would lock the target. As it turns out you have to press the TMS up button on the grip on the stick, (as long as its correctly bound), to lock the target. Not on the throttle. Have you actually tried that? Just mentioned it like four times now.
Cheers!