I'm Tier 5 and I'm trying to get all collectibles and unfortunately I am stuck at 5/6 with the Unknown Echoes category.
I have already completed the "Gatehouse" mission: but I didn't get the collectible.
I can access the underground facility again, I can interact with the computer but nothing happens, the door won't open and I can't access the collectible.
FYI, I have always been playing solo throughout all my story missions.
I would really appreciate some help with this.