Purchase Order - ATO

Summary: Create Purchase Order for Star Item, Options and Mandatory item

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We have requirement to create purchase requisition for ATO sales order. Created a model BOM with model item, option class, option and mandatory item. Create a assignment set for the model item with buy from sourcing rule. Also created a BPA with "Configure to Order Blanket Purchase Agreement" template and add the list price for all mandatory and option items.
Add a sales order with model item and enabled the configurator. In the configurator, I can see all option class and option items but not the mandatory items. Submitted the sales order, PR and PO created for the star item below which it has all option items below their option class. But I dont see any mandatory items even though price is available in the BPA.