Medallions?

Is this whole Vaal temple thing bugged or is it just so convoluted that it makes no sense? I have killed the architect twice now. Both times the quest marker is over the console but when I interact with it I can't do anything. I can select 1 of 3 medallions on the right but the cursor will only go over tiles that already have something placed on them. It won't let me place any of them over existing tiles and it won't allow me to place it on any empty tiles. WTH is the point of this?