For reference, since we talked a bit about this in Slack a few minutes ago:
Site: https://sandbox.jimsimcoe.com/
This is most likely a byproduct of the new Responsive Images that were added to Core in WordPress 4.4:
https://make.www.ads-software.com/core/tag/respimg/
We’ve made some changes to Photon in Jetpack 3.8.1 to be compatible with this new feature, but it seems we haven’t fixed every issue just yet.
We’ll release Jetpack 3.8.2 in a few days, and that release will include more fixes for that new feature. Before you do anything else, I’d suggest trying Jetpack’s current Beta version, since it might solve your issue:
https://jetpack.me/beta
If it doesn’t, could you give me more details about the problem?
1. What happens when you add more slides to the slider? Right now it only seems to include one. https://i.wpne.ws/e6qO
2. Is the slider part of your theme? If so, where can we download a copy of your theme to test things.
3. Is the slider added by a plugin? If so, which one, and how can we reproduce the issue? Do we have to make changes to our theme to add the plugin slider, or is there an option to check after installing the plugin.
4. What computer do you use? Most importantly, is it a Retina / HiDPi machine, and what browser do you use (looks like Chrome, from your screenshots).
Thanks!