Pontem wallet doesn't implement `signMessage` properly

[gsong]

import { useWallet } from "@aptos-labs/wallet-adapter-react";
...
    const { account, network, signMessage } = useWallet();
    const response = await signMessage({
      message: account.address,
      nonce: Date.now().toString(),
      application: true,
    });

When using Pontem, response is undefined. signMessage is one of the standard functions so I would think it needs to be implemented.

The same code works for Petra and Nightly wallets.