Due to some version weirdness with the previous patch in GOG your Save File will have a wrong file name and won't be recognized by GOG Versions 1.02 onwards!

To fix this, go into your %AppData%/LocalLow/AGrumpyFox/Lunistice/ folder and rename lunistice.owo to lunistice-gog.owo.

I'm very sorry for the inconvenience, but this is unfortunately the best fix I'll be able to offer

Whew, I'm relieved it's just that and not a cloud desync or some other issue that would've made the save unrecoverable. Thanks!

PS: .owo has to be the best/most unusual file extension I've seen for a save file. lol

Thank you very much for this heads-up.
I thought I'd have to start over from scratch.

Also thank you for getting 1.03 onto Gog already :-)