Shower door adjustment

I've got the same problem on mine, I shimmed up the hinge, it was fine for 10 minutes and then it did it again.

What I noticed was the upper bracket flexed allowing the door to droop. If I push in on the upper frame, opposite side from the hinge, the bottom of the door lifts and it opens and closes smoothly.

I'm trying to decide how to stiffen up the upper frame to solve the problem.

Worn out hinges or door frame out of square. Push up on outer bottom. My wife tends to push down on the top of the door, Ill bet someone in your household does the same thing.
Remember, these frames are only held together by one screw at each corner, so they move very easily.