Image Lightbox not working from start

I see that some images on this forum have an image lightbox where you can click on an image thumbnail and view the original image. Is there an admin setting to enable this as it does not appear to be working on our forum? I couldn’t anything relevant when searching the settings or this forum.

See Stock Photography. The first image is 811x236 and the markup (which was automatically generated when pasting the image into the editor) is ![image|690x201](upload://yKl0OBbHo9bToKTydZthnnnsTtD.png) . The original image is available If I right-click and open the image in a new tab but there is no light box available when I click on the image.