I have a much worse tale of woe. I played pretty much all night last night, and upgraded 3 cards in my rainbow deck (Electrum Hourglass x 3, Elite Otyugh). The game was definitely saving every time (I've been burned by disconnects before, so I always look now after every win).
Today I log in, go to a game, and am immediately confused when I see *Golden* Hourglass come up. I quit the game, look at my deck, and it's totally downgraded. My Eternity is still there, but that's the only rare card left in my deck. Much worse than that, the rare cards I'd been sitting on from lucky spins were missing from my inventory (Titan and Owl's Eye). The only cards I have in my inventory now are 5 Quantum pillars, which strikes me as incredibly strange, because I have no idea why I would even have ever bought that many Quantum Pillars. So this seems less like a rollback to a save from days ago than it does an across the board downgrade/reset. However, the fact that my score is now ~1200 points lower makes me think that maybe I did get rolled back to an old save.
But if it's an old save file, why do I still have the Miracle I won yesterday?