Sometimes the answer is right in front of you. In other words, it's obvious if you just look. And think.
Looking at the pin (bracket) on the frame, I finally noticed the strike pattern is at the extreme farthest out point on the pin. "Hmmm, maybe the latch is blocked by the bracket?"
So I put in two washers, moving the bracket out from the frame. Now it closes securely and easily. And it locks easily.
Yes, I know, the "correct" solution is probably to leave the bracket where it was and adjust the door closer to the bracket.
But, as a VERY wise Camel Trophy owner once said "Better is the enemy of good!"
Mike & Carrie