When using a MetaMask wallet to view 2017 cards you need to add each card contract manually to MetaMask first. Note: The modern ERC1155 Wrapped Cards will not display in MetaMask using this method. This is only for looking at the native 2017 contract card balances
First, get the contract address for a card from the Card Contracts documentation.
Then in MetaMake add the card address as a new, custom token. Never send cards to the card contract address! You will lose them! Once you copy a card address into your clipboard, make sure you don't accidentally paste it into a transfer transaction later!
Click 'Next' then 'Add Token'
You will now see the balance for that 2017 native card in your MetaMask asset list