Ar10 issues

I have a pretty new ar10, I've ran a few hundred rounds through it and haven't had any real issues, a occasional fte, I took it apart cleaned it and then took it to the range, and out of 20 rd I couldn't get it to cycle, it would extract the brass but not eject it then feed a live round under it, so I figured it was the ammo, so I cleaned it again and tried today with a different ammo and still same issue, the ejector is nice and tight and the extractor works only if I load one round at a time, I'm using a newer (maybe 150rda) 25rd pmag that has always worked before, this is driving me crazy and the manufacturer just says to clean it better