Network Error when using Patch function: The requested operation is invalid

[ppl]

Hello, I have Person or Group Field in my list and I am trying to patch it from powerapps.

Why I am getting this error?

Network Error when using Patch function: The requested operation is invalid

Here is my function:

  Patch(

        List,

        ThisItem,

        {Operator: OperatorComboBox}

    );