Can not import another account - Failed to import account

I’m using a new Brave wallet for months already and besides the main account, I have four more accounts. A couple of days ago I’ve tried to import a new account and it doesn’t work anymore. I’m getting a message “Failed to import account, please try again” all the time so I’m looking for help here.

Are you trying to import the accounts via Private Key or JSON file?

With private keys only.

Is there anything different about the new account that you are trying to import?

No, I just follow the procedure, but the wallet denied it.
This is the scrs of what I’m getting all the time.