Smushing Hung? All Pictures not displaying?

Using Hummingbird to Smush my images - some 900+
Was going well for a few hours, it's seemingly stopped - I was notified by a complaint that pictures were missing from the site (which is live).
The page was left open as demanded.
All plugins are up-to-date running Wp 4.4.2

If you need wp-admin or FTP access let me know how to get them to you via secure method.
Again, this is a live site, I have the option for a restore but as soon as would be good.
Thx