Phantom Item is not exploding in Work Order

Phantom item is not exploding in the Work Order. Whenever we add a phantom item in WO by editing operations items, the phantom item is not exploding, and the parent item is populating the WO items.

Below is the item structure:

Item Structure details:

Phantom 1:

Sub Assembly - 1

Sub Assembly - 2

When we add Phantom 1 item, it has the phantom work definition defined in the system. Our expectation is to show the components (Sub Assembly-1 and 2) in the WO.

Please advise if we need to configure anything or did i miss any step.

Thanks,

Srikar