I had same problem, Angular FormBuilder receives, initial state of control, and verify if the param its like to { value: any, disabled: boolean, ….. } if the parameter meets this struct, initialize the control with value and disabled/active.
try:
this.myFormGroup = this.fb.group(
{
field1: [{ value: '', disabled: true }, SomeValidator1],
field2: [{ value:'', disabled: true }, AnotherValidator2],
field3: [{ value:'', disabled: true}],
...
}
);