1183 Auto-tag fails on '[ ] Save image to tag (if possible)'

If I

1 select tracks in the docked Now Playing window
2 Auto-tag from web
3 Click Auto-tag
4 Untick 'Save image to tag (if possible)'
5 Click OK

MM fails to update the tags.

If I omit #4, it succeeds.

EDIT(TC) Tracked at http://www.ventismedia.com/mantis/view.php?id=6884