Snapshot ignoring uploads folder when backing up

When I run a backup (whether manual or scheduled) the plugin appears to be ignoring / skipping my 'uploads' (media files) folder.

I have tried multiple types of backup (one with just the common files, one with all files, one with just the database etc.) and whatever I try the uploads folder is ignored.

Everything else backs up okay, including the database and the theme & plugin folders, but not uploads folder.

I have also deleted all of the Snapshot plugin files and re-uploaded the latest version, as well as deleted and recreated my Dropbox destination, but this hasn't fixed the issue.

I have the latest version of Wordpress, Snapshots & WPMU Dev Dashboard installed.

Any advice?