How to Implement Partial Auth on Authorize.net API [duplicate] - authorize.net

Question

Okay I am setting up Partial Payments via the Authorize.net API in order to enable multiple cards to be used to cover a single balance/charge.
I'm assuming thier Partial Auth feature covers my use case, but in testing, there is an issue I can show you using the API live console here: https://developer.authorize.net/api/reference/index.html#payment-transactions-charge-a-credit-card
Go to the link above and authorize partial payments with the request I edited below and you will notice when you press submit you get a splitTenderId:
{
"createTransactionRequest": {
"merchantAuthentication": {
"name": "5KP3u95bQpv",
"transactionKey": "346HZ32z3fP4hTG2"
},
"refId": "123456",
"transactionRequest": {
"transactionType": "authCaptureTransaction",
"amount": "462.25",
"payment": {
"creditCard": {
"cardNumber": "5424000000000015",
"expirationDate": "2020-12",
"cardCode": "999"
}
},
"lineItems": {
"lineItem": {
"itemId": "1",
"name": "vase",
"description": "Cannes logo",
"quantity": "18",
"unitPrice": "45.00"
}
},
"tax": {
"amount": "4.26",
"name": "level2 tax name",
"description": "level2 tax"
},
"duty": {
"amount": "8.55",
"name": "duty name",
"description": "duty description"
},
"shipping": {
"amount": "4.26",
"name": "level2 tax name",
"description": "level2 tax"
},
"poNumber": "456654",
"customer": {
"id": "99999456654"
},
"billTo": {
"firstName": "Ellen",
"lastName": "Johnson",
"company": "Souveniropolis",
"address": "14 Main Street",
"city": "Pecan Springs",
"state": "TX",
"zip": "44628",
"country": "USA"
},
"shipTo": {
"firstName": "China",
"lastName": "Bayles",
"company": "Thyme for Tea",
"address": "12 Main Street",
"city": "Pecan Springs",
"state": "TX",
"zip": "44628",
"country": "USA"
},
"customerIP": "192.168.1.1",
"transactionSettings": {
"setting": [
{
"settingName": "emailCustomer",
"settingValue": "true"
}, {
"settingName": "allowPartialAuth",
"settingValue": "true"
},
]
},
"userFields": {
"userField": [
{
"name": "MerchantDefinedFieldName1",
"value": "MerchantDefinedFieldValue1"
},
{
"name": "favorite_color",
"value": "blue"
}
]
}
}
}
}
This is only successful because the amount is 462.25 as the docs say to use for testing, if I use any other (real) amount the splitTenderId is not there.
Here is a new example request, you can post this again on the link above:
{
"createTransactionRequest": {
"merchantAuthentication": {
"name": "5KP3u95bQpv",
"transactionKey": "346HZ32z3fP4hTG2"
},
"refId": "123456",
"transactionRequest": {
"transactionType": "authCaptureTransaction",
"amount": "462",
"payment": {
"creditCard": {
"cardNumber": "5424000000000015",
"expirationDate": "2020-12",
"cardCode": "999"
}
},
"lineItems": {
"lineItem": {
"itemId": "1",
"name": "vase",
"description": "Cannes logo",
"quantity": "18",
"unitPrice": "45.00"
}
},
"tax": {
"amount": "4.26",
"name": "level2 tax name",
"description": "level2 tax"
},
"duty": {
"amount": "8.55",
"name": "duty name",
"description": "duty description"
},
"shipping": {
"amount": "4.26",
"name": "level2 tax name",
"description": "level2 tax"
},
"poNumber": "456654",
"customer": {
"id": "99999456654"
},
"billTo": {
"firstName": "Ellen",
"lastName": "Johnson",
"company": "Souveniropolis",
"address": "14 Main Street",
"city": "Pecan Springs",
"state": "TX",
"zip": "44628",
"country": "USA"
},
"shipTo": {
"firstName": "China",
"lastName": "Bayles",
"company": "Thyme for Tea",
"address": "12 Main Street",
"city": "Pecan Springs",
"state": "TX",
"zip": "44628",
"country": "USA"
},
"customerIP": "192.168.1.1",
"transactionSettings": {
"setting": [
{
"settingName": "emailCustomer",
"settingValue": "true"
}, {
"settingName": "allowPartialAuth",
"settingValue": "true"
},
]
},
"userFields": {
"userField": [
{
"name": "MerchantDefinedFieldName1",
"value": "MerchantDefinedFieldValue1"
},
{
"name": "favorite_color",
"value": "blue"
}
]
}
}
}
}
And with the 462 amount entered this is no longer a partial auth payment and I no longer get a splitTenderId.
Can someone please help me figure out what is going on?