Hello,

I have been looking into your question and I have created a small sample trying to reproduce the described behavior by using the information provided and your code snippet. I am using igx-grid component which has multiple row selection and none cell selection and I also use your template with the igxRowSelector directive and in it I put an igx-checkbox with the handled properties from your code snippet. I add a row with the addRow method when a button is clicked to reproduce the described behavior.

<ng-template igxRowSelector let-rowContext>
      <div>
        <igx-checkbox
          [readonly]="true"
          [checked]="rowContext.selected"
          [disabled]="false"
        >
        </igx-checkbox>
      </div>
    </ng-template>

<button igxButton="raised" (click)="addRow()">Add Row</button>

public addRow(){
        let id = Math.floor(Math.random()*100);
        let row = {
            ProductID: id,
            ReorderLevel: 25,
            ProductName: "Grandmas Boysenberry Spread",
            UnitsInStock: 0,
            OrderDate: new Date("2017-12-17")
        };
        this.grid.addRow(row)
}

On my side everything works as expected and I am able to to add a line and then immediately select or deselect it as the checkbox is fully responsive and can be checked and unchecked.

The described scenario could be observed here:

Here you will find my sample for your reference. Please test it on your side and let me know how it behaves. If this is not an accurate demonstration of what you are trying to achieve, please feel free to modify it and send it back to me along with steps to reproduce and to give me more information about your specific scenario. Alternatively, if the behavior cannot be replicated, please feel free to provide your own sample.

Having a working sample on my side, which I can debug, is going to be very helpful in finding the root cause of this behavior. 

Thank you for your cooperation.  

Regards,
Georgi Anastasov
Entry Level Software Developer
Infragistics