I found out: you should never rely on autosave, only (for now).
Problem:
Sometimes when loading a(ny) game, there occurs an error and the game is loaded with zero staff and zero vehicles. That normally can be solved by quitting and loading the game again, it rarely occurs 2-times, at least at the third load the game is fine, again.
BUT: If you rely on autosave only, the game generates a new autosave when loading (or very early after loading) and overwrites your old autosave with the new data - without staff/vehicles. So your old autosave with staff is gone forever.
Work-around:
So if you (have to) rely on autosave, the only way to solve this, is to make a backup-copy of your autosave-folder in your savesfolder and load that save, BEFORE loading the autosave-game.