The application should be working a lot better on new versions of the app (3.1.0+). If you are receiving no reminders at all, please refer to our troubleshooting guide: https://calendarsnooze.uservoice.com/knowledgebase/articles/1838176-no-reminders-at-all
In the new Calendar Snooze version (3.0.41) we have included a system that syncs the standard calendar database with our own database. The problem is, that in the new Android versions they removed the possibility to detect when a new calendar event is added to the database. This means Calendar Snooze can only sync when the app is opened by the user.
Although this version should be more reliable, we still can't promise a 100% reliability.
The 3.0.41 version should be available to non-beta users by the end of this week.