This also happened to me on Switch and it auto saved. I have this video of the state it was in after the cutscene missing the moon.
I got turned around after returning to the game this morning and wandered back into the game-board area.
@lahutchi - Thanks for the report, if you haven't already done so please click the Me Too button on the first post.
That looks so frustrating! The game should have locked the game board area as soon as you finished the battle, so you can't re-enter it.
I do wish they offered a way to do a "save as", or save the previous version when auto-saving, just so you could revert to the previous save point. At least on PC, I can't find a way to restart a level or revert to previous save point (without manually copying the files before playing).
