Please take a look at how the mission 'Enemy of my enemy' (Rat king quest story-line mission) is possibly keeping the door as a 'Locked' status for players who never picked up Sloane's quest from Y1 thus never doing this mission ever. And since a decent chunk of Destiny 2 players could care less for the Rat King they are now being inadvertently locked out of being able to start the 'Outbreak Prime' quest.