While this issue isn't consistent, I've had this happen to me often enough that it's a problem (over half of my runs of this strike). During the Exodus Crash strike, when players reach the Glade of Echoes to fight the spider tank, in some instances, there is just a skiff sitting above the area where the tank should be getting dropped off. This results in a bugged waypoint that tells the players to continue towards the boss encounter. However, the trigger for the barrier that walls off that room doesn't get hit, because the tank was not spawned/killed by those players, and therefore does not drop. One other thing that might attribute to this problem, is each time I've seen this occur, there have been either other strike fireteams or solo players in the instance before mine enters it. I hope the information I've given helps.