Sign Typed Data API not working

[michaelzrrr-2]

I'm trying to get a lazy-mint call to work for Rarible, which requires me to sign a typed data structure. Here is the data I am tried to sign first, ``` const msgParams = JSON.stringify({
domain: {
chainId: 4,
name: 'Mint721',
verifyingContract: '0xB0EA149212Eb707a1E5FC1D2d3fD318a8d94cf05',
version: '1',
},

message: {"chicken":"bruh"},

primaryType: 'Mint721',
types: {
  EIP712Domain: [
    { name: 'name', type: 'string' },
    { name: 'version', type: 'string' },
    { name: 'chainId', type: 'uint256' },
    { name: 'verifyingContract', type: 'address' },
  ],
  Mint721: [
    { name: "tokenId", type: "uint256" },
    { name: "creators", type: "Part[]" },
    { name: "uri", type: "string"},
    { name: "royalties", type: "Part[]" },
  ],
  Part: [
    { name: "account", type: "address" },
    { name: "value", type: "uint96" }
  ],
},

I am able to sign this using MetaMask, but the signature is invalid for minting (which makes sense since the message is bogus). However, when I change the message to this

      "@type": "ERC721",
      "contract": "0xB0EA149212Eb707a1E5FC1D2d3fD318a8d94cf05",
      "uri": uri,
      "tokenURI": uri,
      "tokenId": tokenId,
      "creators": [
        {"account": "creator", "value": "10000"}
      ],
      "royalties": [
        {"account": "creator", "value": 2500}
      ],
    },

now, after I click sign on my wallet, the signTypedData() call will never complete. Any ideas why this might be the case, or is there a different way I should be getting a valid signature for minting?