The save system in Baldur’s Gate 3 is having some problems. Namely, some players are having trouble saving or loading the game. Larian has directed players to a help page that should hopefully solve the issue if you’re running into this. You can’t get back any of the progress you lost due to a busted save.
There is a bug in BG3’s cloud sync service that prevents players from saving or loading while the game works fruitlessly to offload data to the cloud. Players experiencing the bug report the game becoming trapped in an endless sync loop, preventing them from saving or loading.
According to Larian’s support page for players who can’t save, they recommend deactivating “all non-essential programs” before you launch the game, “especially any anti-virus and backup programs” that might interfere with the game’s ability to manipulate its own data.