Hi Simon, I think I’ve got a fix for you. Just add this to your themes functions.php file:
/* Check for and add theme support for post-thumbnails */
if ( function_exists('add_theme_support') )
add_theme_support('post-thumbnails');
The problem is, not all themes will have support for post-thumbnails added and we use this function in the plugin without checking to see if support is added first. We’ll be patching the plugin to check for this which will fix it without the need for adding anything to functions.php but this is a temporary fix.
Let me know whether or not that works.
Cheers,
Jonah