Irradiation doesn't work at all.

Hello,

I try to get 80+ level maps and it's impossible to do. Basic map and XV waystone makes level 79. If i put the same waystone in irradiated map, it's still on 79. I can only make 80 level map using XVI waystones.

https://www.youtube.com/watch?v=bFB1r1259do

Could you fix it?