Happiness Rating Error 400 On Save

Happiness Rating Error 400 On Save

I am getting an Error 400 when trying to save any setting change in Happiness Rating and the yellow boxed Loading message pops up and never disappears. If I reload the page the settings are all unchanged.

The error I am getting is:

POST <Our Support Url> 400 (Bad Request)

If I paste the above redacted URL in the web browser and load it, it loads the Happiness Rating page ok.

Tried in IE, Chrome and Firefox, same error in the console/firebug.

Any suggestions?