I followed this tutorial to mint NFT https://www.youtube.com/watch?v=YN8HAlM6YW0&feature=emb_title
Contract Address: 0x031117bdca935b1f754ba65b6deeb608b08b9495
Opensea: https://testnets.opensea.io/assets/mumbai/0x031117bdca935b1f754ba65b6deeb608b08b9495/637891851694329631
But return token_uri and metadata null?