Firstly you need to have quest in notebook to follow her, after this, she go to gym at sunday and wednesday, you need skip part of the day after night and you have 2 options follow her or sleep, you need to select follow and mc talk about invisible, maybe you broke quest somehow or script. in post above i gave my Mega link to saves, download it and select save and search what you need.
If it is really bug as you say , maybe your save or game is bugged and there is only help from DEV at this point, then try my saves.
![1621160159722.png 1621160159722.png](https://attachments.f95zone.to/2021/05/thumb/1219243_1621160159722.png)