I lured Erandur to the sacrificak post and slew him with the blade of sacrifice, Boethiah took over his body, but I can't talk to her! Every time I activte Erandur's inhabited body, she keep's saying "You have drawn my attention mortal. That is most unwise."

Nothing more, no talk dialogues.

Done the entire quest chain with no issues whatsoever here,must be something on your end m8

I'm having the same problem after luring Marcurio there. Reloaded and tried with another person as well, but nothing happened past Boethiah taking over the body.

Edit: I managed to get past the part it was stuck at. I sacrificed Lydia this time, but it still didn't work, so while Boethiah was in Lydia's body and my vision was all weird, I killed all of her followers at the shrine. She went into a new body, and I was finally able to speak with her. I hope this works for you.

Same issue with not being able to speak to Boethiah once she has inhabited your sacrifices body. Going to try CitrusKiss suggestion...will post on result.

That worked, however I had to search the area as the new inhabited body was at the bottom of the stairs, not up on the platform where the fight took place.

i killed the poor lacky i hired to die with a completely different weapon.. and it triggered the whole sequence.

So can't really say why it's not working... may require using a console command. of which i'm not sure.