Backup to computer isn't working

Backup to computer.
Browse around for a while after initial backup to store new data.
Run the backup again.

Object { _e: Error, name: "DataError", message: "No key or key range specified.", inner: DOMException, stack: "", … }

DataCloneError: The object could not be cloned.

Is this bug acknowledged? Initial backup seems to work fine without any problems. It fails consistently if I try to run backup again after the first backup.
Doing full backup every time is not an elegant solution.

Hey Matt,

Thanks for the post, bug acknowledge and part of the bugfixing hunt we do when the first version of the sync and mobile apps are out.