In the plugin-folder is a .htaccess with one single line
Options -Indexes
try to comment it out
#`Options -Indexes
Hey,
I have the same problem in a theme for a client I am working on. The button is only missing, if the custom post type DOES NOT SUPPORT ‘editor’ and if the image have been uploaded in this custom post as a featured image so it is attached to this custom post type.
If you change 'supports' => array('title', 'thumbnail') to 'supports' => array('title', 'thumbnail', 'editor') you will see the “Insert Image” – Button.
I have tested this in various themes with different code and the problem was always there. I think this is wordpress bug.
