The one that is giving me trouble is a Magpul. The other Magpul that I have works perfectly.
The one that is causing problems seems to not raise the cartridge high enough, so the bolt will travel right over the top of it instead of scraping into the firing chamber, and this causes minor damage to the surface of the bullet and its casing on top of jamming the rifle.
I’m not sure if the damage is severe enough to make the bullet dangerous to fire after clearing it, but I have not tried to fire on of these, so it basically wastes a round each time this happens.