That's a strange issue?!

At first glance, my guess was permissions (which it may well be). But then you said other images (which I assume were uploaded in a similar fashion) were displaying fine?!

As per our recent discussion on updating Ghost, all the folder permissions should be right. And if it was uploaded via the Ghost UI, it certainly shouldn't be a permissions issue (if Ghost could save the file, surely it should be able to read it again later?!).

So possibly the first thing to check is what error the image is giving. You note that it appears that image link is broken, so chances are that will be causing a specific HTTP error code which will assist with troubleshooting. So if you can right click the image (or where it should be) and "open in new tab" (if it allows that). Then in the new tab, you should get a clear error message. My guess is 401, 403 or 404, but it might also be a 50x error.

If you can't do that for whatever reason, then another way to get the same info is via teh web browser "developer tools". These days, all browsers should have the option to show a developer console. E.g. for Firefox it's "Tools > Web Developer > Web Developer Tools"; for Chrome it's "Chrome Menu (in the upper-right-hand corner of the window) > More Tools > Developer Tools). With the dev tools open, you should be able to view errors and the error(s) related to your images should show there (plus likely a ton of other warnings that you can safely ignore).

Apparently Ghost's internal logs aren't that helpful (or so I've read), but the Nginx logs might also give some value? They should be found /var/log/nginx/error.log.

I hope that helps. If not, please let me know (plus any relevant info you've dug up in the meantime).