How Do i get into the atlas room again after i left?

I got in the map room after finishing cruel but didnt activate anything since i wanted to kill a boss that i missed. I cant seem to get back there in any way.

I tried killing the last boss of act 3 again but he just doesnt have any text options after the fight.

It doest show up on my map or anything. What do i do? is that a bug?

Did you figure out how? I did the same thing.

Derp. Found it 1 minute later at the bottom middle of the last act's map.