Stuck doors suck

The latch mechanisms are a little touchy. If it isn't all the way to one position or the other they will hang. This what happens when the striker post moves away from the latch. The latch stops short of its fully closed movement. We can just about bet on the door being down a bit also ( worn hinges ) which is what pushed the striker post away.
What to try... Lift the outside handle and push the door toward closed with much force.
If the latch does complete its movement it will operate again.