I'm not sure anyone ever communicated the real reason for this issue. The safeties don't do it, just the decockers do it. Not all years of manufacture do it.
If CZ worked on it and figured it out no one every went on line and explained what they found. Shhh. It's a sequet?
Some people who really wanted to keep their pistols figured out a way around it and that's something to do with dimpling either the right side lever or the left side shaft, I don't remember which. There are some posts on the forum here about it.
I run the safeties and never had the issue on either of mine (naturally).