When I launched Griftlands on Steam this morning, all of my unlocks and save data were gone. Taking a look at the save folder, it appeared a new folder had been created, named steam-76561198779325704 and the game now appeared to save in this folder instead of the usual steam-76561198054787819.
I have not switched Steam accounts or anything of the sort, and my Steam ID is 76561198054787819. Pasting the data from the original folder to the new one worked to be able to keep playing on my regular save file.
Launch the game
Go to the Compendium
Everything is at 0%
Go to the folder that contain the save files folder
See that there are now three save folders (one for Epic, two for Steam)