Seems the Mark IV like many .22lr semi auto handguns can be a little finicky with ammo. Look on the popular Rimfire forum, here, and elsewhere for discussion.
My MK III Target had very little issue with a variety of ammo--it was real shooter. But I sold that a long while back. My MK IV Hunter 5.5 blued has had issues. Mostly extraction of spent round issues. Now maybe I have not shot it enough yet. Still under 1000rds. Last time at the range, I only used CCI Mini Mags round nose. Had a few extraction issues with two magazines. Continued to use just these two magazines the rest of the firing session. Towards the end of the session I had no issues. I have installed a new extractor and I have tuned up 1/2 of my magazines. Of the two magazines used that I had issues one was tuned, one was not. Next range trip I'll be using the CCI's again. Will likely sand all edges of remaining un tuned magazines to deburr-smooth edges, including the follower channel.
Use cleaner more quality ammo for better performance is what I hear all the time.