"...is not ejecting"?
Please be more specific.
Is only the first round not ejecting? Random rounds? Only the last? All the rounds in the magazine?
Does the empty shell end up right back in the barrel's chamber? Or does it "stovepipe"?
If you number each magazine, by writing on a piece of tape stuck to the floorplate, are you absolutely certain that it's happening only to those two magazines?
More information, and maybe even some photos, would be useful.