ugh. sorry you had so much trouble! thanks for writing it up.
publishing to Instagram from third party apps is difficult and often broken precisely because Instagram wants it that way: [http://developers.instagram.com/post/133424514006/instagram-platform-update](http://developers.instagram.com/post/133424514006/instagram-platform-update)
they allow a very short list of use cases in their API, and this isn’t one. services like SNAP reverse engineer their apps and scrape their HTML. IG doesn’t even want apps _reading_ photos or feeds, so Bridgy and OwnYourGram scrape too, which is obviously brittle, and heavily rate limited. sad.