I was granted early access to Minecraft Dungeons Hero Edition through Xbox Canada. 

I played through the entire game on Windows 10 PC. And today (May 26th) when encountering the "Cannot verify game ownership" I tried reinstalling the game.

After doing so, I managed to connect to the game and discovered my entire progress is missing. I'm back at the "hero" character creation screen at level 1.

My Xbox Gamertag is "TheChiefCanuck" and I have the achievements showing I completed the game.