Does anyone else's P22 slide catch a tiny bit on the hammer as it's racked and released? I've noticed if I very gently ease the slide from completely racked to its normal position, I can get it to hang up on the top edge of the hammer. If this is normal, I would bet this is the reason high velocity ammo is a must, as lower velocity and subsonic bullets wouldn't produce enough blowback to fully cycle the action, which would cause FTF/FTE problems.
I just checked mine and the slide DOES catch slightly on the inside top of the hammer when you cycle the slide slowly. Can't notice it normally. But I doubt that has anything to do with FTF/FTE problems if you have them. I shoot Remington subsonic almost exclusively when I shoot with my suppressors, which is a lot of the time; nary a hiccup of any sort. Same results without the cans.
Otherwise, it can be very picky about ammo. I've found Remington to be one of the most reliable brand in my P22. Also, try to use jacketed rounds, that can help decrease the malfunctions also.