There is a problem with Borderlands 3 save data on PC. Some players lost all their progress for some reason in BL3. There is a way to possible fix this issue.
- Open the Epic Games Launcher
- Go to Settings
- Uncheck the "Enable Cloud Saves"
- Go to C:\Users\*your username*\Documents\My Games\Borderlands 3\Saved\SaveGames\*mixed letter folder*
- Before you make a change, you should paste the save file to another folder.
- After that, right-click on the .sav file
- Click on Properties
- Go to "Previous Versions" tab.
- Select your latest save time
- Click on Restore button
- Also, you should do same thing for profile.sav file
- After you've done it all, launch Borderlands 3.
I hope it helps you. Unfortunately, there is nothing else that can be done for this save data issue.
By the way, you must disable the cloud saves to avoid this problem.