Disable does not work on the Material Toggle Buttons

[Crystal O'Mara]

I can't get the Material Toggle Buttons to become disabled (please help!):

1. I've tried passing true = "[disabled]="true""
2. I've tried binding a value that was true 
3. I've tried just placing the "disabled" attribute with no binding

<mat-button-toggle-group
  aria-label="Choose Location Identifier"
  value="searchByAddress"
>
  <mat-button-toggle
    (click)="searchByAddress = true"
    value="searchByAddress"
    [disabled]="true"
  >
    Location
  </mat-button-toggle>
  <mat-button-toggle
    (click)="searchByAddress = false"
    value="searchByCircuit"
    disabled
  >
    Circuit ID
  </mat-button-toggle>
</mat-button-toggle-group>