Remember to make sure you're online on the internet -EVERY TIME- before you start the game to avoid this. Satisfactory is an online game and must be online to play it correctly. If you aren't online then the game won't let you resume your character. It will spawn a clone of you near by and all your stuff will be gone and sometimes you won't be able to access anything you built either. This isn't a bug, it's how the game is coded/designed.