My progress is lost / not stored if I restart the app!
Please try to reinstall the app. This sounds like a permission issue. Also make sure you have a bit of storage left on your device. If you are on iOS, you might also have success by disabling the iCloud sync within the app’s settings page.
/!\ Please make a backup of your data with the cross-sync or export/import function before deleting the app. Deleting the app will also delete the remaining progress! /!\