I installed the Performance trigger in my Gen G19, this was the latest version that came with a Gen 5 backplate for use in Gen 4 guns.
Trigger felt good on dry fire but on first live fire the slide would lock back every shot. Investigation revealed that the trigger shoe was pushing up the slide lock. The relief cut on the left side of the shoe was at a different angle than on the stock Gen 4 trigger shoe. It wasn't low enough and was pushing up the slide lock.
I solved the problem by replacing the Glock shoe with an Overwatch Precision Polydat shoe that I had on the stock trigger bar.