You may have noticed that since Monday, that the Picture of the Day, nor the Albums display any photos. The issue is not with me using the wrong code to link the photos that are stored on Flickr, but some issue within WordPress.
The problem started with an update of WordPress which included a new Text Editor called Gutenberg. The update mention that the Gutenberg editor would become the default with the soon to be release of WordPress Version 5. It suggested to tryout Gutenberg now, which I did. The result being that the photos would not show. I removed Gutenberg and went back to use the Classic Editor. However, it made no difference, the photos in any posting, over 600, would show up. I reinstalled WordPress and the Photonic plugin, it did not solve the problem.
I am currently working with the developer of Photonic to get this problem resolved. It may take some time until this is done because of the time zones and other restraints. If you want to see the set of photos for a particular day, use https://www.flickr.com/cameraroll and goto the day you are interested in. If you just want to see the photos go to https://www.flickr.com/photos/klausnaujok/