don't trust FN's polymer pistols. I don't think they do enough testing before releasing them, and every FN polymer pistol other than the Five-seveN has had design issues that could stop the pistol from functioning.
I'll trust that the issues you described are real, though I never heard of them researching the FNX/FNP I ended up not buying (for a Five-seveN instead). FWIW, the vaunted Five-seveN had (s) a stupid design flaw that can tie it up extremely easily;
On my second range trip, I guess the top-most round in the mag wasn't fully back. Upon inserting the mag, the tip of the round snagged the mag-release spring, and popped it right out! The instant I removed the mag, the spring and release catch fell to the ground. No positive way to hold the mag in anymore (without your hand, I guess). No way to drop the hammer on a chambered round without a mag in the well (mag safety). If someone was doing tac-reloads where they might not be carefully tapping every mag against their boot before loading, this issue could easily come up.
To their credit, FNH realized the issue, and developed a quality fix, which they promptly sent me free of charge. Replaced with a machined leaf spring was the cheesy bent paperclip that
was the mag release return spring.
My point is, nearly all gun designs (especially new ones) have issues. The FNP and FNX are
today highly respected in the identically-performing-polymer-pistol category. Heck, the Beretta 92 series had it's share of teething issues, as I recall, and they have legions (literally) of fans today.
TCB