Pokemon-go – No Pokestop’s, Gyms nor Pokemon appearing in a non geo-blocked region of China

I saw a few questions like these. I did a lot of research myself to see how I could fix the problem, and this trick did it, so I thought I'd add my two cents, and so this can also help future readers.

Why is Pokemon Go not Working on WiFi?

At the first launch of the app, a setting must have been selected automatically that restricts data access to the Pokemon go app.

How to fix the problem

Go to:

1. Settings of the phone
2. Go to the apps section of your settings
3. Click on "reset app preferences" in that section (for my Galaxy S7 I click the three dots at the top right of the screen first)
4. Launch Pokemon Go

More on resetting app preferences in this article by TechRepublic.

Downfalls

This will reset the app preferences for every app, which means that when you launch an app, it will again ask you a prompt for access to a certain feature on your phone. For example, Gallery will ask for permission to your photos the next time you open it, just like Pokemon Go will ask for permission to your camera.

This happened to me a few days ago. I was with 4 friends and only one space in the gym (we're all in the same team) and only one of us could put a pokemon in the gym. It turned out to be, that the game I think has a bug that only enables the first person who entered the gym to add pokemon and so on.