Can browse internet with Safari but other apps cannot access internet

Apps are showing popups "cellular data is turned off for app".

I am currently out of my city, which is why I first thought the reason could be that I dont have access to cellular data. But when I open Safari I am able to browse on every site, which means my data is active.

Why are other apps giving popup that I dont have data on for the app?

I have checked in settings and data is on for the app (whatsapp) I want to use. Please let me know how can I solve this.