Have used the plugin before on other sites with great success. Installed on current site, and it simply doesn't work. When I click Smush.it now! on an image in the media library, it works for longer than I would expect and then, when it stops working on it, nothing has changed. The file still shows as not processed.
Here's what I've tried: Deactivating and reactivating the plugin; uninstalling and reinstalling the plugin; disabling caching plugins that do anything to image files.
Any help that can be provided would be appreciated.