Please try the following:
1. Go to Settings> Apps> See all Apps> Find the App> Storage & Cache> Clear Storage and Clear Cache.
2. Swipe up the home page to enter the recent app page, clear all applications and then try again.
3. Uninstall and reinstall the application.
4. Back up any important data and restore your phone to factory settings.
If the issue persists, contact the Nothing Support Team for further assistance.