I finished the TG quest line ages ago, and I decided to go to Nightingale hall today to find Karliah. Except, when I went there, I couldn't find her at all, even though she said she'd make Nightingale hall her home (used Aura whisper to detect signs of life to make sure, nothing showed up).

Anyone know where she might be? Or is this a bug?

i had this problem as well. Go to Winterhold, enter the Frozen Hearth, then go down into the Frozen Hearth Cellar. I'm almost certain she'll be there for you.

Edit: at least that's where she has been for me after completing all of the Thieves Guild, and I'm on Xbox as well. Hope that helps.

I checked there already. She's not there

Try Snow Veil Sanctum? That's usually where she goes. It's a bug, happened to a lot of people.

Yeah, Snow Veil Sanctum was going to be my next place for you to check. In all the Karliah glitches I've seen those are the two places she normally stays.