Ionic 4 - Angular 6 formArrayName not working as expected

Trying to use formArrayName with a list of ionic checkbox
This is my control:

this.planGroup = this.formBuilder.group({
        ...
        PlanEmails: this.formBuilder.array([
            this.formBuilder.group({
                PlanId: '',
                EmailId: ''
            })
        ]),
    });

And this is my HTML

         <ion-row>
            <ion-col formArrayName="PlanEmails" [sizeXs]="12" [sizeSm]="6" *ngFor="let email of emails">
              <ion-item>
                <ion-label></ion-label>
                <ion-checkbox formControlName="EmailId" color="secondary" [value]="email.Id" slot="start"></ion-checkbox>
              </ion-item>
            </ion-col>
          </ion-row>

This is the error I'm getting

ERROR Error: Cannot find control with path: 'PlanEmails -> EmailId' at _throwError (forms.js:1732) at setUpControl (forms.js:1640) at FormGroupDirective.push../node_modules/@angular/forms/fesm5/forms.js.FormGroupDirective.addControl (forms.js:4454) at FormControlName.push../node_modules/@angular/forms/fesm5/forms.js.FormControlName._setUpControl (forms.js:4959) at FormControlName.push../node_modules/@angular/forms/fesm5/forms.js.FormControlName.ngOnChanges (forms.js:4909) at checkAndUpdateDirectiveInline (core.js:9246) at checkAndUpdateNodeInline (core.js:10514) at checkAndUpdateNode (core.js:10476) at debugCheckAndUpdateNode (core.js:11109) at debugCheckDirectivesFn (core.js:11069)

Tried moving formArrayName to ion-row and to ion-item and it didn't work.
I don't know I'm doing wrong. Tried reading Angular documentation but I can't seem to figure it out.

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