For both the Custom Post Navigation and Author Box elements, the php code in the element (accessed and edited from the Elements page) seems to not be getting processed on the server. Instead it is output as an HTML comment partially and partially output as text; the raw PHP code is displayed on the page.
The page source for the author box is pasted below. Is anyone else having this problem?
Just after I posted my topic I went to one of the Elements in question and noticed this (finally): Unable to execute PHP as DISALLOW_FILE_EDIT is defined. I just changed hosting environments and the default wp-config.php file includes a definition for DISALLOW_FILE_EDIT as FALSE. I removed the definition, and checked the “Execute PHP” box and the now the code is executed.
That resolves the problem. Still, I must ask: What does file editing have to do with the execution of the php in GP Elements anyway?