If you already have all the Training H-Scenes → simply sleep in your room at bedtime.
If you don't have them yet → meet Sayo in the Gym during the Morning to trigger her third romance event. After that, train with her in the Gym one more time.
Once you've completed the required step above, go to sleep at bedtime to unlock Vision 2.
You can try joining the discord if this still won't work.
