The app backups every time you open a calendar. The backup date is updated when the app is closed completely and reopened. Swipe app closed and reopen. Check if date is changed.

If your backup date is not changing you can try two solutions.

  1. Visit settings and hit MANUALY BACKUP -> swipe app closed and reopen. Did date change?
  2. In older app remove old calendar events. Too Much data will prevent app from backing up.
  3. In newer version of app. Visit Settings -> Click Reduce Data. Swipe app closed and reopen. Check if date has changed.