To clarify, the "updated" version of Minecraft I'm referring to is the "Better Together" update. When I opened Minecraft Xbox One Edition over a month ago, it informed me of the "new version" and offered it to me freely. I downloaded it, merged (synced) my world to the new version and played it that way. Always remembering to save it. But it always worried me that there were now TWO separate versions of Minecraft on my Xbox One, and that all my newly saved data went to "Better Together" since that is where I was playing. When I performed the factory reset of my console last night, I chose the option to keep current apps and games. BOTH versions of Minecraft were still available. However, "Better Together" version no longer had my saved data but I could select to sync my old world from "Xbox One Edition". The problem here being that the most recent saves weren't registered to the original edition so performing a sync on an old world meant all progress had been lost since I had begun using "Better Together" version, since that version now had ZERO available saved data.
Again, PLEASE comment with any information or advice. Losing something of this magnitude is truly upsetting and I would LOVE to get it back.