In all image fields of templates that are made with After Effects (these are the templates that get status ‘transcoding’ in the clip library after creating them), the image fields are optional. This means that when creating a template, you can skip the image page without uploading or selecting an image. When you do this, you will see the background of the template on screen where the image normally is. You will not see a standard image or something else that indicates that an image can be placed there.
In widgets (these can be recognized by the status ‘widget’ that they get in the clip library) this isn’t possible.
Click here for more information about creating a clip.