How to send Date picker value over REST/JSON

Hello, I’m have a form on my website that create leads im my CRM system (MyBusiness - based on Simbla framework).
I am sending various data which is received well on the other side and creates the lead perfectly. the only thing I can’t get through is the date value from the wix date picker.
I’ve tried to send the value, the ISO string of the value, different date formatting. nothing seems to work - I either get an error " “schema mismatch for Accounts.IDIssueDate; expected Date but got String” or the CRM returns success and creates the lead but leaves the date field empty

Some more details:
The field in the lead form/DB is of type DATE
Here is the code I’m using to send the data (from the corvid backend):

export function postToMB(formFields) {
 const url = "https://apps.simbla.com/parse/functions/run_function?functionName=getlead";
 const headers = {
 'Content-Type': "application/json",
 'X-Parse-Application-Id': MY-APP-ID,
 'X-Parse-Master-Key': MY-APP-MASTER-KEY
  };
    
 const data = JSON.stringify({
 "Name": formFields.fullName, //text
 "PhoneNumber": formFields.phoneNo, //number
 "City": formFields.residance, //text
 "Age": formFields.age, //number
 "IDNum": formFields.IDNum, //number
 "IDIssueDate": formFields.IDIssueDate, //date picker - here lies my problem
 //formFields.IDIssueDate is sent from FE as date.value (which is a string)
 "PassportIssued": formFields.passport, //bool
 "outAbroad": formFields.abroad, /bool
 "Email": formFields.email, //text
  })
 const request = {
 "method": 'post',
 "headers": headers,
 "body": data
    };
    console.log("ADDING LEAD @@@@@@@@@@@@@@@@@@@@@")
 return fetch(url, request)
        .then(response => console.log(response.json()))

}

I’m quite rusty so it maybe a very very basic error.
Thanks in advamce

This is strange, because if JSON is agnostic about 1 data type, it´s a Date. Have you tried sending it as a number, as in millisecs using getTime() or getUTCMilliseconds ()?
If that doesn´t work, you should contact the CRM-manufacturer and ask which format they need (or maybe it´s documented?)

Hi, I will try sending it as you suggested. The CRM has poor documentation and the is out until Monday so no luck theree.
Thanks