Zencastr saves local backups of each participant's track while you record. The browsers have two categories of local storage that is available to browser based applications. 'Temporary' and 'Persistent'. Temporary storage runs the risk of being deleted if the participant is low on disk space while persistent storage can only be deleted if the users explicitly allows it.
The browser hasn't granted zencastr.com access to persistent local storage.
From the Chrome developer documentation:
Chrome will automatically grant the persistence permission if any of the following are true:
- The site is bookmarked (and the user has 5 or less bookmarks)
- The site has high site engagement
- The site has been added to home screen
- The site has push notifications enabled
Adding Zencastr to your Chrome home screen and / or bookmarking zencastr.com should cause Chrome to grant persistent storage to zencastr.com
The user should be prompted to allow access to persistent storage when they first load zencastr.com