For 10 years I backed up with the jaws closed on my 16K. I watch the handle move out and slam shut to tell me I'm there. Only twice did I forget to lift the tab on the handle which keeps the jaws from opening.
When I couldn't disconnect, it was usually because the truck had rolled forward slightly putting pressure on the back of the jaws with the pin. I would just put in reverse and back up a tad and it would release. You can also have the issue if you lift the pin box too high and it puts upward pressure on the jaws.
I put Air-Lift bags on my last truck with a compressor and automatic leveling system by Air-Lift. When you raised the pin box up off the hitch, you had about 25 seconds to disconnect and move or the bags would release air and the truck would lower itself putting pressure on the jaws and it wouldn't release. I would cuss and my wife would laugh.