Hi there,
That’s the direct image link from your server that Mehdi mentioned in the last reply. It appears there is a cache issue and that’s why the image is loading for you but not for us.
And from what you mentioned I think there is some kind of plugin feature conflict here. It could be a cache plugin you may have installed.
The quickest way to figure out if something is interfering is to test for a theme or plugin conflict. I know it’s less than ideal, but could you please try the following:
Temporarily deactivate all the site’s plugins except for Jetpack and clear your browser’s cache. Then try loading image again. If it works, then we’ll know that another plugin is conflicting here. You can re-enable your plugins one by one, trying loading image in between, until you find the one causing the conflict. You can leave it disabled or reach out to the plugin developer for a fix.
If disabling plugins doesn’t help, it may be the theme. Temporarily switch your theme to a WordPress default theme like Twenty-Twenty. Then try loading image again. If it works, then you know it’s a problem with the theme, and you can reach out to the theme developer for a fix.
Let us know what you find!