This add-on used to work really well a few months ago but now it just keeps randomly removing the check boxes to delete scrobbles, as much as i liked this add-on in it's current state, it's unusable.
Dev, If you need any additional information feel free to let me know, i'll be happy to help.

The extension has a "can't read and change data on this site" error when you try to click on it. Completely grayed out.