Check the stripper on the bottom of the slide. I've not heard of it on the CM but early on some didn't have a bevel and it would ride over the cartridge without getting behind it, so it didn't pick it up.
You can lock the slide back, and insert a loaded mag and see if the round slips up in front of the stripper bar. Not sure that's a proper name but that's what it does. Might just need a bit more taper since it's not happening often.
In Memory of Paul "Dietrich" Stines.
Dad: Say something nice to your cousin Shirley
Dietrich: For a fat girl you sure don't sweat much.
Cue sound of Head slap.
RIP Muggsy & TMan
"If you are a warrior legally authorized to carry a weapon and you step outside without that weapon, then you become a sheep, pretending that JOCKO will not come today."