Use this guide to resolve any issues with Metamask.
Wallet is not connecting to Trader Joe.
Make sure you do not have other wallet extensions running at the same time. If the ‘not connected’ MM message is blank, select it to connect. If you can now see your address showing up in the Trader Joe UI, you've connected a wallet.
I transferred tokens, but I cannot see them in MM.
You need to add a new token in MM. You can do this by selecting import tokens at the bottom of the MM app and inputting the custom token details or searching for them.