However changing the theme to a default one works fine. The problem is I’m developing the theme and could really use this button, the old system and prior to 3.5 the feature worked fine.
I’m not even sure where to look for what could be causing the error, it is an extensive theme and has many many new features added to it.
I use “WPAlchemy MetaBox PHP Class” to assist in creating the admin menu but as far as I am aware this is not a know fault with that system.
I have deleted all the files, uploaded a complete fresh version of wordpress 3.5.1 and then re-added the theme, it didn’t solve any issues for me.
The only error I get with debugging turned on is
Notice: load_plugin_textdomain was called with an argument that is deprecated since version 2.7 with no alternative available.
Can somebody please point me in the right direction.