Sure! I don't think I had beta access (I downloaded the publicly available demo, that wasn't beta, right?). I made saves within the demo, but was not using those - I downloaded the full game off itch.io and started from scratch. I deleted the demo just now and tried playing the full version again, loading from a save I made within it, but got the same error. I'll try playing the full version from scratch again and see if it works now that the demo has been deleted.