Hi This is on a Multi site platform
Network activated plugins
BJ Lazy Load
BruteProtect
Change WP Mail From Details
Contact Form 7
Exclude Pages from Navigation
Flamingo
Join My Multisite
Lightbox Plus ColorBox
MailChimp for WordPress Lite
MCE Table Buttons
NextCellent Gallery
Q and A FAQ and Knowledge Base for WordPress
Really Simple CAPTCHA
RV Embed PDF
Share Buttons by AddToAny
Spam Destroyer
Terms of Use
Thin Out Revisions
Ultimate Google Analytics
Use Google Libraries
User Role Editor
Video Manual for WordPress SEO by Yoast
White Label CMS
Select WordPress Importer
WordPress MU Domain Mapping
WordPress SEO
Plus these plugins that the site we noticed it stop working on which it had worked in the past.
Advanced Recent Posts Widget
Black Studio TinyMCE Widget
Disable Post Locking
eStore Voucher Generation Addon
WP Coupon Generator
WP eStore
Not sure if you tested with a multi-site should of mentioned that first I guess. But late tonight I will try deactivating plugins to see if I can work out if one of them are having an issue as I have updated some since your plugin was working.