Apex Legends – Anti-Cheat Authentication Error [4] When Trying to Queue (Steam)

Hi everyone, I'm having an issue with EA AntiCheat in Apex Legends. I launch the game through Steam, and everything works fine until I try to queue for a match. Then I get the error: "The client is not running the anti-cheat, or has failed the anti-cheat authentication. (4)"
I've already tried several fixes, but nothing has worked. I checked Windows Services, and the EA AntiCheat Service is running with the startup type set to Manual. I also checked Task Manager, and the anti-cheat process is running while Apex Legends is open.
So, the anti-cheat appears to be running correctly, but the game still fails authentication every time I try to join a match.
Has anyone experienced this issue or found a working solution? I'd really appreciate some help because I can't play the game at all.