Arlathan Forest Shadowy Grove Puzzle Not Completing

I have been trying to 100% the maps prior to going into the end game and the only chest I have remaining in Arlathan Forest is the statue puzzle in the Shadowy Grove.

I interact with the letter and then move all the statues to the correct location. They make a noise suggesting I did it correctly and I can no long er interact with them. But then... nothing happens.

 Googling suggests a rage demon is supposed to spawn, but I am not getting that. I have done laps of the area, approached everything and... nothing.

Anyone else also having this issue?