This is both a bug report and also a way for people to know what causes this bug so it can be avoided. When doing the step in "The Ritual" section of the campaign where you need to kill Savathun's illusions, pick up the glass breaker, then deposit them, players may run into an issue where Savathun's illusion doesn't drop a glass breaker. When this happens it bugs this part of the quest so that it has to be restarted since you wont be able to get the 3 glass breakers needed. If someone doesn't know the cause of this, it's very possible it'll happen multiple times causing a lot of frustration. The bug occurs when a Savathun illusion dies while the guardian who got the final blow is dead or has died & got revived before doing any more damage. This can occur when someone is using any type of weapon or ability with a delay in the damage. Grenade, rockets, rockets with lasting impression, poison like on the osteo striga or le monarque, etc etc. If Savathun's illusion dies after the guardian has died it will drop no glass breaker and will Not respawn either, making it impossible to get the 3 needed to open the portal. At that point the only fix is to go back to orbit. If needed I can post a video of the bug in action, but hopefully the description is enough for it to be looked into and eventually fixed. So best to avoid anything on Savathun's illusion that does any kind of delayed damage. Hopefully this bug will be fixed eventually as I know it's caused some frustration with people who must have been using some kind of poison weapon or something with a damage over time. Had it hit our attempt tonight a few times in a row on the legendary campaign.