Hi there
Thanks very much for your response. I’m sorry I was a bit vague in my description. It turns out that the plugin in which I am adding the shortcode is to blame. I was experimenting with something called Media Grid, and the author has just informed me that it is impossible to display shortcode within the overlays as I had hoped.
When I tested the shortcode method in a regular post, it worked as described in your documentation. As long as there is a valid field entry for that post!
Thanks again!
