I just checked and it's working fine with me. Did you talk to the lady twice? All the shops in Huyuchi have a little introduction before you can start using their services.
Viewing post in Witch Hat & Ears of Cat comments
That's so weird!
If you walk behind the counter to talk to her model directly, nothing is supposed to happen. But if you stand in front of the counter facing her and press Z the dialogue window should pop up just like with any other merchants. If you're using a mouse or playing on mobile, you may have to click/tap twice, once to move your character in place, and once to actually talk with her.