ATP isn’t honoring supply from the specified subinventory, even though it’s added to the sales order

ATP is not honouring supply in a specific subinventory even when the subinventory is added to the sales order.

We have a requirement where stock is kept in specific subinventories for different types of client businesses e.g. B2B stock for the same customer is kept in Subinventory Sub1 and B2C stock for the same customer is kept in Subinventory Sub2. Now during order entry and booking, based on same customer, but different order type, we default Subinventory Sub1 for B2B and default Subinventory Sub2 for B2C. But when we click on order level ATP, Global order promising checks the supply of both Subinventory 1 and Subinventory 2 to provide material available date which is not correct as the expectation