I had a bad Steel one when they released their first pistol. I sent it back and it still didn't run, I did what I always do, I dumped it.
15 years later I hear the PM9 is the bomb now, I picked one up that was used real lightly, "from a gentleman", and he already replaced the mag release with the steel one, and sent the gun in for Kahr, to polish the internals, and mag release along with the barrel.
"For the sake of full disclosure".
He may have done the work to clear up some of the issues you speak of. I had the same problem with the shield 40. Every 4th or 5th round, the mag fell out. Made sure my finger was no ware near the mag release.
These small guns require some tinkering sometimes to get them running right.
They also can suddenly go out of sync for several reasons. Springs, ,mags, extractors, etc. It's what we have to deal with when shrinking down a full-sized gun to a pocket gun. It can happen with any of them, from my experience. You need to spend the time to get yours right or move onto a different model. It's not any particular gun, it is the luck of the draw sometimes.