I have two Kel-Tec pistols. A P32 I bought used, in the original box. I don't think the previous iwner even cleaned the factory protectant out of it. Maybe even didn't shoot it. Lots of ftf problems with the first couple mags. Also failure to return to battery. After a good cleaning, and lube it got a lot better. My other Kel-Tec is a PMR 30. Similar, but not as sever problems at first. I haven't shot it a lot, but it did show signs of improving.
I think maybe their guns just need a good amount of running in to work reliably. Not used to that. My Ruger LCP, Kahr CM9, Springer XD40 Sub Compact, even Hi-Point C9 all ran 100% from the very start.