You could take the magazine apart and with the slide off, look down and see if the mag release is getting full engagement. Might be a burr or something causing it not to fully enter the slot.
Could be maybe the mag is a tad off, if you have more than one and they both act the same, then of course that's probably not the issue.
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."