Something about your setup is weird.
If I issue a GET to this URL I get a sequence of redirects:
GET → 307 → 302 → 200
However, if I issue a HEAD I get a 200 straight away
HEAD → 200
The way our onebox works is that we try to handle all the redirection dance with a HEAD request first, and pass the already resolved URL and the necessary cookies to the oneboxer engine.
Since your setup is doing different responses for each, this breaks onebox. It’s also quite bad for perfomance when the canonical URL for the article is always two redirects away from rendering, so you may want to fix that.