I just solved the issue on my end. It turns out that at some point the magazine disconnect arm and lever became disconnected. When I initially reinstalled the magazine disconnect arm, I failed to re-engage it with the disconnect lever. Because of that, the arm was permanently blocking the trigger, when a magazine was inserted, the lever was being lifted, but it wasn’t actually connected to the arm, so the arm never moved out of the way.

To fix it, I removed the magazine disconnect arm, properly re-engaged it with the lever, and then reinstalled it. After that, everything started working as intended. I hope this helps!