Slider Not showing any images

Site has been up for months and working fine. No changes in the slider configuration have been made, but the site is no longer showing images in the slider. Anyone else having this problem?

To rule out the obvious – the Slider category exists, is populated and each post has a Featured image. These images are present on the server as referenced by the posts, and all of these images previously displayed properly. The issue appears to be the same on mobile and in all browsers tested.