Angular Button Disabled/Enable back is not working with Formly(reactive forms)

Question

Thank you in advance for helping me with this problem.

I am unable to enable back the button, I have 3 components where the actual button which need to be disabled is present in A component.

Flow:

On A component load, there is a popup shown which is from component C and on clicking Approve button from component c, in component B emitter function hits and I am emitting Boolean as false in that function and subscribing to it in component A and assigning the value to the property which is making the button disabled, but button still remains in disabled mode only.The local property in component A is also getting assigned false but the button still says in disabled mode only.

I used BehaviorSubject of type boolean and made the initial value as null.

Component: A

.html

<button[disabled]="(processing$ | async)" kendoButton>

.ts

processing$ = new BehaviorSubject < boolean > (false);

ngOnInit() {
  this.userMessageService.currentQRMApprovedStatus.
  subscribe(
    isQRMApproved => {
      if (isQRMApproved)
        this.processing$.next(false);
    });
}