I’ve had an Advantage Arms LE 17 kit for several years and have had very few stoppages with it and certainly nothing like you seem to be experiencing.
Look closely at the chamber area and extractor to see if there are any burrs or other obvious problems. Hopefully a trip back to Advantage can cure your issues.
Called AA and they wanted me to email them some pictures, that was on the 21st, as of this date & time they haven’t replied to my email.
Waiting for their reply, I read on another forum about spraying the rounds with a lubricant. Therefore this morning I sprayed Ballistol on the rounds prior to loading in the magazine and big as dogPoop it worked. They also specifically state that you MUST use HV ammo, that standard velocity (SV) ammo will not work. They go on to state NOT RECOMMENDED any Win ammo etc. Well this am, spraying PMC 40gr SV & Win M22 40GR HV worked like a champ. Rem Gloden worked without the spraying.