Corrupted maps are NOT giving a +1 monster level

I'm trying to get the points 7 & 8 of the Boss Atlas, I already got the first 6 and I know that in order to do so, I need to kill a boss on a map with monster lvl 82.

That said, I go to a Corrupted area, select a map that it's corrupted, irradiated and has a boss, I'm using a corrupted lvl 16 waystone, and the BUG is that it's still showing as a lvl 81 monster map.

I haven't cleaned the corrupted nexus close to and I also haven't failed it, I didn't even tried it yet.

Am I doing something wrong here or is this a bug and the corrupted maps are not actually giving a +1 monster level ?