I'm setting up a new site
Neutica+ theme which is a child theme of Thematic.
The theme know how to recognize the first image in a post and set that as the post thumbnail.
I wanted to select a post thumbnail that will not appear in the post itself, so I've added the command to the theme functions.php which ads the option in the admin.
Uploaded an image to a post, works ok so far.
The strange problem is when I want to change the thumbnail image to an image already in the media library- I click "set as thumbnail", it saves, but nothing changes on the actual posts.
At the moment, it seems like I can only define a thumbnail image from a file I am uploading for the specific action, does that make sense?