You can see in the screenshot I link to below that the reason the thumbnails aren’t showing is because they can’t be found on your server. Looking at the url, it seems they are trying to load from a /cache/ folder.
http://picpaste.com/d9f014ad5df9d873226c981df550fa6a.png
If you have a caching plugin or have caching on your host, try clearing your cache.
If that doesn’t work, try this plugin to regenerate thumbnails on your site.
https://wordpress.org/plugins/regenerate-thumbnails/
I cleared the cache but still see broken images. I disabled the caching and still see broken images. I also installed and tried out the regenerate thumbnails plugin, but it’s still showing broken images.
I’m going to keep researching and trying things, but wanted to update the ticket with what I’ve done. Still unresolved.
I have noticed issues like this a lot lately too.
For example this site I am building http://gravitas-digital.com/services/photography/ the gallery at the bottom just shows the loading icon infinitely. Any ideas what this is?
I have another site that’s doing the same thing, sadly. Didn’t used to but just started recently (not sure exactly when).