0.3 Bug - "Merging World" atlas passive not working

Hi!
In my map, an "Owl Spirit" possessed an Essence Monster, but afterwards, it only had one spirit. I have the 'Merging World' passive — shouldn't the monster have been possessed by two spirits?
Here is the video of the bug : https://www.youtube.com/watch?v=qYT_gkQtxbM
0:00 - 0:34 : monster possessed.
0:34 - 2:50 : skip, I just manage my inventory in my HO.
2:50 - 3:20 : Atlas tree.
Thanks!
P.S. : Awesome league !!

Edit: I also noticed it just now with a rare monster (not essence).