FTE suppressed?

New to the FN game. Got myself FDE FNX 45 tactical. Took it to the range few things I noticed. I did not like the red dot site that came with the gun. (Vortex viper). Handles well is a tack driver. I did drop a magazine a couple of times bumping the mag release. Anyways I threw my YHM cobra on the gun and it wouldn’t extract the case. Confused because I would think it would have more gas. Anyways any ideas on this???