Please make sure your game and system are always up-to-date. Without the game's official patches your are running the risk of encountering errors of various kind, while save files from an older, unpatched game will be incompatible with a patched version of the game.
For PC users, old saves (any saves made before Dec 20th's Early Access Update) can cause the Load screen to not show any saves and instead an indefinite loading symbol. The solution is to delete any old saves from your save game file.
For console users, any saves made without the Day 1 Patch will NOT work after updating.