Insert lead via API V2 with 'Custom Fields'

Insert lead via API V2 with 'Custom Fields'

I'm trying to insert new CRM leads using API V2.

The leads are created however the custom field "Notes" is not being saved.

What am I doing wrong?

Here is the body of my post:
{
    "data": [
       {
            "Company": "Zylker",
            "Last_Name": "Daly",
            "First_Name": "Paul",
            "Email": " p.daly@zylker.com",
            "State": "Texas",
            "Notes": "My Notes",
            
        },
       {
            "Company": "Villa Margarita",
            "Last_Name": "Dolan",
            "First_Name": "Brian",
            "Email": " brian@villa.com",
            "State": "Texas",
            "Notes": "My Notes2"
        }
    ],
    "trigger": [
        "approval",
        "workflow",
        "blueprint"
    ]
}