Dunno.. I've heard people having this problem for a long time.. I just park the trailer, hold the brake, put truck in park, set parking brake. Put wheel choke on trailer.
Lift tongue up on hitch to take WD bars off. Lower tongue back down. Release latch. Lift tongue back up and it always just comes off.
Do this at different angles of the truck pointing in all kinds of different directions or up or down.
Good luck!
Mitch