It says that her story hint says "Go to her dorm" , did you finish Chapter 2? Abigail will only be unlocked if you finished Chapter 2 and also the option to go to her hut in Vrakia should still be there because of these conditions
1. If you started her side-story
2. If she's unlocked or joined your group
3. If the time of day is morning, afternoon, evening
Edit: at n5, that' s an old bug like a really old bug. I don't see any jumps or ways by clicking on her option to jump to Ayane's dorm by looking at the code. What version are you in?