I just checked it again, without cache. Medium is still showing my stories to me, when I am logged in. When I log out, it's medium.com/suspended on all of them. No reason was stated, nor have I received any communication from them (nor they from me).

They don't expect original content only, actually they have "Import your story" feature where you just enter your Steemit (or any other) link and your external article is automatically imported for publishing on Medium (it doesn't work 100% correct, so some extra-formatting is usually needed, but it was useful enough).