I have somee Item in the media library, where I want to retrieve the thunbnail from. I use the normal post thumbnail functions (tried some of them), with normal posts or cpts's the work fine.
As media library items are handled, similiar to posts, I thought the normal wp thumb function could work there, too. There are also thumbs created, as i can see on the server.
But no one fo WP's Thumb Fuunctions returns that thumb.
Here an example Function, I use:
<?php echo get_the_post_thumbnail($post->ID, 'size-1'); ?>
The post ID is correct. The Thumbnail size is registered and works for other posts fine.