A recently discovered Apex Legends bug causes Gibraltar's own shield to either block his shots or causes the hits not to register. The bug was shared to Reddit, and it didn't take long for Respawn to respond, "Just curious, but if you have a friend also in the game, do they see you shoot a bullet? Does the bullet still hit for them? Info on what another player sees would be super helpful! Thanks :)"
It seems the bug is hard to replicate despite significant evidence of it existing. Other players even chimed in about the shield bug happening in their own games.
Apex Legends Gibraltar Shield Bug Blocks His Own Shots
As for a fix, Respawn released an update on Wednesday which fixed another exploit by Rampart. It could be another week before Respawn drops a hotfix that targets Gibraltar. And it could be even longer if Respawn can't replicate the bug or find the problem. Something is triggering the bug and it could be as simple latency problems or as complicated as a coding error.
Until then, be patient and avoid the quick shield, ADS move shown in the video.