Excuse me, but I'm testing if it works and it works fine for me. Are you sure you are talking to the right person? She is this girl, in the gym. If it's her, haven't you had the bad luck that she just disappears when you go to talk to her because time passes? She leaves the gym at 16:00 and then she comes back at 20:00. Have you tried talking to her at a good time?
If you have done all of the above, have you done anything in your game apart from strictly completing the main story quests, have you done anything even minimally different? Anything could help me detect the bug.
