The one that resets all your loadouts to only AR, Pistol, and Frag. I do not expect 343i to comment on this thread, but I hope they see it and start working on a fix.
It’s really annoying, yes. Hopefully it’ll be fixed in the next update or two. However, I’ve noticed in my Sniper Loadout that the Primary is still a DMR Noble when the glitch happens, but everything else resets.