Which console are you on? Your profile says Xbox One, but the way your talking about transfer from cloud make it seem like you are on PS4.
On Xbox it's possible to delete locally stored save data and download it again from Xbox Live the next time the game starts. Please note it's not really a backup feature but a method to synchronise data between multiple consoles, and to protect against hardware failure. The cloud copy of the save data is updated whenever you start or exit a game (if you turn off the console before it's complete it will resume again at next start), so if the game quit with bad save data the cloud will get updated with it.
Exploration map data is stored together with the character (before 1.3 on console it was stored with the world). If you lose the character, that is gone as well and it's not possible to recover it.
Somehow the character data got corrupted. Do you know what happened?
Save data can get corrupted if the game crashes while saving, or if the game/console is shut down while saving.