Dynamcis 365 - Ribbon Workbench - A custom Button on SubGrid not visible

Question

I have added a new button to the Product Sub Grid on the Order form. for that I did following

1. Added a custom button
2. Added a command
3. Assocoated command to the Button

4. Added Enable Rule for the command button via calling a JS function from Web Resource

However, this button is not visiable on the Subgrid. I have tried debugging using command check but the button is not visisble on command checker as well

1. Ribbon XML does have the info about the new button
2. Command checker doesn't show that button on the subgrid