Can't recreate off chain signed message on Solidity

Im using Nethereum on my server to sign a message as follows:

string amount = "10";
string nonce = "1";
string msg1 = "asdasd";
var privateKey = "0x00000privateKey";
var signer1 = new EthereumMessageSigner();

var abiEnconde = new ABIEncode(); 
var byteArray = abiEnconde.GetABIEncodedPacked(msg1,amount, nonce);
var messageHashed = "0x" + Convert.ToHexString(byteArray).ToLower();         
var signature1 = signer1.Sign(byteArray, new EthECKey(privateKey));

signature comes out perfect, the problem comes when I try to recreate the message with its variables in solidity as follows:

function VerifyMessage(bytes memory sig,string memory msg1, string memory amount, string memory nonce) public pure returns (address) {
    (uint8 _v, bytes32 _r, bytes32 _s) = splitSignature(sig);

    bytes memory prefix = "\x19Ethereum Signed Message:\n32";
    bytes32 prefixedHashMessage = keccak256(abi.encodePacked(prefix,msg1,amount,nonce));
    address signer = ecrecover(prefixedHashMessage, _v, _r, _s);
    return signer;
}

The signer is not the wallet that I signed with Nethereum off chain, however, if I try to instead to pass messageHashed from the server instead of recreating the message, it works perfectly, so I think the problem is in the solidity function. Ex.:

bytes32 prefixedHashMessage = keccak256(abi.encodePacked(prefix,HASHED-MSG-FROM-NETHEREUM));

this works fine.

This is how I got it to work

 var abiEnconde = new ABIEncode();

 var resultHash = abiEnconde.GetSha3ABIEncodedPacked(
          new ABIValue("address", msg1),
          new ABIValue("uint256", amount),
          new ABIValue("uint256", nonce));

 var messageHashed = "0x" + Convert.ToHexString(resultHash).ToLower();
 var signature1 = signer1.Sign(resultHash, new EthECKey(privateKey));

And in solidity:

function getMessageHash(address add,uint256 amount,uint256 nonce ) public pure returns (bytes32) {
    return keccak256(abi.encodePacked(add,amount,nonce)); 
}

And to recover the signer>

 bytes memory prefix = "\x19Ethereum Signed Message:\n32";
 bytes32 prefixedHashMessage = keccak256(abi.encodePacked(prefix,getMessageHash(msg1,amount,nonce)));
    
 address signer = ecrecover(prefixedHashMessage, _v, _r, _s);