I dunno, just doesn't for some reason I know it's an issue with a lot of CZs.
I don't want to do modifications that 75Plus described.
Inter the Slide Stop in to the Frame without the Upper installed
Then inserting a Magazine, and see if the Follower raises, or tries to raise the Stop, but can't
If it tries to but doesn't, or it only moves a little, then your Slide Stop Spring is too tight
If it doesn't even try, then you're using the wrong Slide Stop
If it raises (fully), then there's some-other issue:
You may be using the wrong Slide Stop or there's an issue with the Stop Notch in the Slide / Bolt
If you think your Slide Stop Spring may be too tight, try this:
With the Upper off, insert the Tip of the Slide Stop in the Right (opposite) Side and rotate it several time in each direction
Do this a few times and it can help to loosen the Slide Stop Spring a bit