I found a solution that works, but only on Redmagic smartphones. you have to go into Game Space and force the screen aspect ratio to 32:9, which will enlarge the game like in PC mode, and then click anywhere on the far right in the black area—and normally you’ll be able to tap the professor. It’s actually a bug: the professor, who is the required interaction to advance the story, is hidden in the black area.
For those who don’t have Game Space or a Redmagic phone, I don’t have a solution—sorry.