Jetpack's Twitter Timelines are broken on my websites, I only noticed today but it may be since yesterday idk. They were working before...
I read this topic which is a year old: https://dev.twitter.com/discussions/10808
and I noticed that in fact, inspecting with Chrome's developer tools, the script for platform.twitter.com was "//platform.twitter.com" instead of "http://platform.twitter.com" or "https://platform.twitter.com". It should pick up the protocol from the href location ("p=/^http:/.test(d.location)?'http':'https'") but for some reason it isn't working right in the jetpack widget.
That might not be the only problem, I tried doing a custom text/html widget, pasting in twitter's generated script code, but it still doesn't work even though the "https" is in there too, the error is:
Failed to load resource https://platform.twitter.com/widgets.js
Failed to load resource https://apis.google.com/js/plusone.js
In that same discussion it says you need to insert your domain and "www" third-level domain in a whitelist, but apparently these whitelists no longer exist? I guess that's something that twitter has to answer though...