I had a similar issue with a bolt a few months ago, along with it failing to fully go into battery it also would fail to eject spent cases, the cases would be literally stuck to the bolt face. I checked several things including the ejector spring and extractor, and they were all fine, replaced them with known working parts and it still would happen.
It ended up that the inner diameter of the bolt face was slightly undersized. It was cut at .374 while SAAMI specs for the rim are .378. When I had brass that had a rim of around .376 the cases would get stuck and it was hard to even force them onto the bolt face by hand. This was causing both the failure to go into full battery and the failure to eject the spent round.
Rubber City was great about it all and I sent them the entire BCG and they replaced the bolt and since then I have had zero issues with several hundred rounds down range with it. Before it was happening at least once on every mag. None of the previous problems have come back.