It’s random but I’ve been having issues with enabling cellular data on some apps I’ve downloaded.
When I first start the app and it asks to use data I choose WiFi and cellular data. It’ll then warn me that there is no internet connection. I’ll then proceed to settings/cellular data and find the app, it’s in the off state. Once I go into it and choose either WLAN or WLAN & Cellular Data and go back it remains in the off state.
I’ve tried reinstalling the apps and it seems this setting is saved in the phone. Again, it is random which apps this happens to but when it does it’s not fixable.