Had problems with latching in down position, but this has been greatly improved by suggestion from Thule product manager. Grasp top of carrier frame in left hand, bottom of frame with right hand, and rotate by pulling out on bottom and pushing in on top -- you should hear the latch snap into place.
Locking has not been a problem, as we loop a locking cable around the mounting foot of the bar and use bar locks.
I also hope they will extend any fixes to us beta testers. I would not have purchased a new product in its first year, except that the operation would have kept me off the water otherwise.