I've checked in a number of magento 1.9 demo sites, as well as my own but can't work out what's stopping it being shown in all the responsive emulators - screenfly etc... Anyone shed some light on this for me?
This is caused by the X-frame policy, Magento has a built-in feature that denies calls from an iframe.
Screenfly uses such an Iframe to display the content. To solve this , you can enable the proxy in screenfly (the eye-button) or change to following setting in your Magento.
Go to your adminpanel
And set the "Allow Magento Frontend to run in frame" to Enabled.