You might encounter this issue because not all of the desired pictures have the same resolution. Bulkr is configured to download images of the same resolution, but, for example, if you have a picture in Large mode and Bulkr is configured for Medium size, then it will try to get the Medium size version of the picture. Since there is only Large one available, Bulkr will not be able to perform the operation and display the following error "This image or video is unavailable".
