We have an app that is partly powered by a WKWebView. For various reasons irrelevant to this question, we're using a local webserver to serve content and act as a proxy to the WKWebView. The local web server is http (and not easily changed to https). The webview's baseURL is https. In iOS 8, we received console warnings about loading insecure content (as expected). In iOS 9, it appears the requests to the local webserver are sometimes blocked, and sometimes not, as indicated in the screenshot here: http://d.pr/i/11Tvy/36DWnMtt+
Most are marked as [blocked], however the second one is not, even though nothing from the warning would indicate why that one would be allowed through and the others not.
Is there any insight as to why some requests are blocked and not others, or under what conditions a request is blocked?
To be clear: I'm very aware of why this warning is being printed, and why loading http from https could be a bad idea. I'm not asking that the warnings or blocks be removed, since I understand and sympathize with their purpose, just for more insight into why some are now blocked and some are not.