Apparently "Shared Links" no longer works in Safari 11.0 - see e.g. http://www.openradar.me/33142258 though I only saw this today for the first time when Apple pulled a Microsoft and auto-updated Safari (apparently, anyway). See this picture for how it looks now - there should be three tabs on the far left.
Any notions on what happened here? I assume there is a plist I can search through to at least see whether it just lost all my RSS feeds, that would be helpful, though if someone has a hack that would be better.
(Yes, I have attempted to use other free RSS readers, but they don't integrate as well with ordinary web browsing as this by a long shot.)