Help me ! item bugged ! iris rank 4

I have finished the achievements Battle for Azeroth keymaster
Yes i have done +15 mythic timed on all.
i finished it today 1 august 2020 im like YES i can buy IRIS RANK 4 at the vendor but I CANT the item is sold 75 titan residium… i tough it was 800? and i cannot buy it… its bugged? whats happening