My PT111 Mil-pro (3rd gen) will not allow me to rack the slide. A round is chambered and I don't know what to do. Earlier on it did the same thing with an empty chamber. I had to pull the trigger and it released the slide. I may have to wait until I get to the range in order to shoot out the round, Is this a bad idea? I removed the magazine and tried again, but it remains locked. What could be the cause of this all of a sudden?