I have a custom post type called Artwork. In addition to having several custom fields associated with it, it also has the standard Featured Image (post thumbnail) field associated with it.
Not all Artwork posts will have a Featured Image. I'm trying to create a view that retrieves a list of 5 random Artwork posts that have a non-empty Featured Image field. I tried to create a filter on the view, but Featured Image isn't one of the fields that appears to be filterable (see attached). Is there a way to accomplish this?