I have tried switching the phone off and on etc and have definitely used data (including right now) but the app isn’t showing any data used and is asking that I use an app that uses data.
Did you get our app from Google Play or are you using an APK from somewhere else?
Can you delete the app then reinstall from Google Play, then when it asks you to allow “Usage” be sure you switch it to on during the setup process.
What phone/OS version are you using? Go to the top left menu and choose “send feedback” then send us logs, thanks.