Guin - Aoiichi
Yes in season two. But remember in season four , when she is inside the tree of time , the spirits can not sense any "Raava energy" in her. So what i am suggesting is that Raava's "mission" is over. Vaatu was defeated therefore she can go back to the spirit world. But then you might say "what about season three?" And i'd say yes Raava was still with her up untill when Opal's mother removed the poison. Then maybe somewhere in Korra's mind/inner spirit . Raava and Korra parted ways? I mean Raava no longer needs to stay with her. Now im not saying Raava wanted to leave. But maybe Korra's fear of the avatar state made Raava leave? This is just me guessing. Remember that is Raava's power that initiates/maintains the avatar state. And that time Korra has no control. I think i can understand where Korra's fears are coming from. She looses control of her own body and is the closest she has ever been to death.
Just going to pop in with my two cents here real quick:
The fact that the spirits can't sense her Raava energy is due to the fact that she is spiritually and mentally divided; the trauma she suffered after being forced into the avatar state and nearly killed forced her into a defensive position. She is afraid of that part of herself, because being the avatar, something she eagerly embraced at the beginning of the series, has suddenly become terrifying. She was faced with the enormous weight of almost becoming the last avatar, which is a failure to the entire world, for the rest of forever. She lost control and could not do anything about going into the avatar state, so now she is terrified of the avatar part of herself. Just like Toph said, part of her would rather just be unwell so she can hide from the world and not face the horror she had to deal with as the avatar with Zaheer. She is afraid of facing that part of herself. Raava is still there, but Korra has that entire side of her blocked off, and her fear is why it is confronting her so violently. Plus she was never super spiritual to begin with, she had only just begun to come to terms with the spiritual side of herself and the avatar state, only to be put in a position where its used against her, so it makes sense that she's so afraid of it.