apple books offline

Hi!

The issue’s been bothering me for weeks since I’m a massive iBooks user... Every time I open my Books it just keeps saying “you are offline”, and when I go to settings to allow using cellular data and WiFi for the app, once I go back to Books the setting option will just TURN IT OFF!!! So I’m stuck right here, the setting won’t allow me to use data for the app... (looking for solution😡