C# API Record update INVALID_DATA error

C# API Record update INVALID_DATA error

Hello,
I'm using official .NET API lib (ZCRMSDK) and trying to import products. But I'm getting maximum length error when try to submit large string to a custom field. In field's properties length is 32000 characters. 

What am I doing wrong?
{
  "data": [
    {
      "code": "INVALID_DATA",
      "details": {
        "maximum_length": 1000,
        "api_name": "Ingredient_Statement"
      },
      "message": "invalid data",
      "status": "error"
    }
  ]
}