Hello,
Yes! I've been seeing the same problem, so thank you for the tip on switching to 'Original' size!
Of course, that now leaves all the instagram thumbnails in the slider with different heights, so I worked around that secondary problem by adding ".instagram-image-around { max-height:160px; overflow: hidden;}" into the page CSS. (You will probably just need to choose an appropriate height to suit your own needs - 160px worked of for me.)
PS Don't know if anyone else noticed the same issue, but for several weeks prior to these images disappearing, I've noticed that some elements on my page were randomly displaying behind a translucent white overlay (looked like white fog) which I suspected was due to a timing issue with JS running this YOLO instagram slider. Refreshing the page was generally enough to "fix" the problem, but it was very annoying. I only mention in case it's somehow related.