Hey @fbslo, I assumed the burn action need to be carried out in the website, if someone did it onchain using burn method, it won't work. I read through the code, is really simple and straight forward on the smart contract code.

I used to have some code written back in the days when Hive first released, https://github.com/superoo7/BSwap

I created a method call burnToBC, where the params accept username so that the token can be transfer back on blockchain

    /**
     * @dev Destroys `amount` tokens from the caller.
     *
     * See {ERC20-_burn}.
     *
     * Requirements:
     *
     * - Blockchain `username`
     */
    function burnToBC(uint256 amount, string memory username) public {
        _burn(_msgSender(), amount);
        emit TokenBurnToBC(amount, username);
    }