@Shamram You have one of two problems, or perhaps a combination of two.
Scenario 1:
I see you mentioned “starting fresh.” If you did a reset of your device or anything changed in regards to your OS user account, then you would have lost the encryption key to your passwords. Passwords are encrypted using our OS keychain, which is our password and OS account.
Trying to paste in your \brave-browser folder would carry the old encryption but your changes would have you using a different key. As such, no password would be visible.
Potentially you could kind of test this by doing a new browser profile and then import the CSV you have.
Scenario 2
There is a currently known issue that occurred in the more recent updates. I address this at Aggregate Topic: Lost Passwords in July 2024 update
Similar to scenario 1, something is happening to cause passwords (or a password) to become "corrupt, leading the browser to be unable to decrypt it . When a password can’t be decrypted, it assumes there may be a security breach and it will refuse to decrypt any of the passwords.
There is a potential workaround using the command to skip undecryptable passwords, which allows all other passwords except the “corrupt” one(s) to load. Or you could even just try to revert/downgrade to a prior version of Brave, as people are saying passwords then show.