Was doing Legend Seraph's Shield with a friend and we got soft locked due to the issue in the title. I think that the mission objective might not have changed to acquire the keycard iirc, but I may be wrong about that. Restarting the mission fixed it.
-
Usually if it bugs out, its a early checkpoint update that was missed. Bungie are aware of it but as we're less than 2 weeks away from Lightfall its unlikely to be fixed.
-
I kept running into this issue, I had to slow down in the start area. if you enter the elevator room before the enemies spawn in you bug out the level's checkpoints. once you kill the ogre and are going in try slowing down and walking. it worked for me. good luck!