The remedy is simple, fix Mingle. In the absence of that you can fix it using the following method:

1. Open mingle.php
2. After the PHP comment for the plugin at the top add the following code

   add_action('init', 'mngl_init');
   function mngl_init() {

3. Right at the bottom of the code before the closing ?>, add the following:

   }

4. Save the file and then plugins like mine will work with it without causing a conflict.

If either the Mingle author fixes the problem or anyone has a better way of sorting this then please do let me know and I will update this post to let others know.

Please make sure you back up the mingle.php file before making these changes. Just in case Please also be aware that if you update the Mingle plugin then you need to put this code in again to maintain the fix.