The gate being closed on Lincoln Tunnel, doors shut on the Consulate or Lexington, it really just happens far more often then it should.
This morning it happened but none of us moved forward. The leader switched the difficulty a couple of times ending back up on Challenging. At that point we moved forward and the mission allowed us to start (doors swung open). I have only seen it done once but have been locked out dozens of times so it might have been a fluke.
yeah they really need to fix this, an actual reset mission option for the leader could help.. bit of a no brainer. i have spent 30mins+ some times trying to get a functional instance and a group of decent players for missions and incursions. im not sure if there is a trick to it, i relog if i was previously in a failed instance attempt.