How to fix xcode bug "web filter is active"? [duplicate]
It took me some research to figure out what's going on but what you are running into is Safari 10's "enhanced content security policy" in action.
E.G. you might be loading your page from a remote server via https://, but the page itself requests images via non-encrypted http:// URL's.
See if you can find out what image URL's are being loaded and then add the domains to your App Transport Security exceptions.