I've met her in the woods at night when she told me to go to her hut in Devenant, and I have agreed to help her find a subject. I've done this after first finding my way to the orc den under the Arena. I thought the fact I was fast traveling could have something to do with it, so I tried (after meeting her in the woods + her hut) fast traveling to Noria's Inn and manually going to the Arena and taking the trapdoor again, but I still have no "call the witch" option when talking to the orc guarding the trapdoor in the Arena.
Since it seems it's only affecting me, I doubt it's a bug and it's likely the fact it's interwoven with several other quests that I've put on the backburner to try and reach the futa content (which is admittedly my main draw, so I'm a bit on the backfoot on the idea of having to clear up all the other quests before reaching my goal), would be my guess.