I had an early one. While I didn't have the striker rotation problem, occasionally the slidecover would slip down and catch on the frame rails.
On the right, you can see the plate has slipped down. CZ's fix was to bevel the slide cover so it wouldn't catch.
The reason CZ added the square notch wasn't necessarily to prevent the hangup issue. If the striker assembly drops down a bit, the trigger pull essentially gets longer since you have to pull it a greater distance to drop the trigger bar clear of the striker. Some people had issues where the striker wouldn't release with the trigger fully to the rear. By limiting the downward movement of the striker housing, you get a more consistent break. Similar in effect to dry-firing with without a magazine installed. It makes a bigger difference than you think. When I was doing trigger tests, I mapped the difference between a loaded mag pushing the slide to it's highest position on the rails, vs no mag and the slide free to drop down.