Found out the reason!
I had played on a save on alpha 3, and recently updated to alpha 6, alpha 6 had succesfully recognised there were previous save games, but was looking for game objects that have since been renamed or are no longer used.
The solution for windows was to go to the save game folder (C:\Users\username\AppData\Local\Forager) and delete any previous saves, seemed to be the only thing that worked.