When I first got my MK II, it did the same thing, I thought it was the ammo, switched up and the same thing kept happening...so I finally changed out the extractor with a Volquartsen extractor and the problem went away. It will spit out any brand I feed it with no problems. We did the same thing with my Dad's MKIII 22/45.
I have an MKII that I think also has this extractor. Feeds and ejects pertty darn well. Sure is a very accurate gun.