FYI
The slide stop is lifted by the magazine follower when the magazine is empty. It would hold the slide stop up while you were testing it.
FYII just got back from the range and I noticed when I was seating my mag hard into the well g23 gen4 it was releasing the slide by itself. My first guess was that I had a bad extended slide release lever and I switched back to my factory one but that didn't solve the problem. I also thought maybe I had a bad magazine and that wasnt the problem. It happens with all three mags.
The weird thing is it doesnt happen when the magazines are unloaded. I have tried my hardest to make it happen with a unloaded mag and the slide will stay locked back no matter what. Im confused and Im looking for some help. Thanks.