I was wondering if the ‘upload to’ field in media library is informational of functional?
Because, it’s often incorrect.
For example, I created a post. I uploaded an image as the featured image and published the post. In the media library, the image was attached to this post and looked great.
But, when I deleted this original post (I permanently deleted the post from trash)and created a new post, set the image I had previously used in the deleted post as the featured image; it still remained listed unattached in the media library.
I have many images which show their status as unattached in the media library, but they are either featured images in posts or pages or images in the postal page.
I’m wondering if this is a problem functionally with WordPress , or is whether an image is ‘attached’ Or ‘unattached’ is just informational nice to have but okay if it’s incorrect?
It’s not a problem with WordPress. It’s how it should be. If you see the image below of media library.
You can see that the column name is Uploaded to which means that media file was not there before and it’s introduced or uploaded to the below mentioned post/page/etc.
Since in your case it’s uploaded to the old post and not new post the media file is in detached state, as while you were creating the new post the media file was already there, so the Uploaded to doesn’t really fit here.
Although I sometimes feel that Attached/Detacthed is a bit confusing.
Basically here Attach/Detach refers to the registration of the media file to the particular post while uploading to the Media Library and not whether it is used in the post or not.