As per SAID: 49183 | Revenue Recognition Rules,
When the source transaction includes a posting discount, all elements in a revenue arrangement use Default One-Time Direct Posting rule.
This is standard behavior and currently logged under Enhancement 480902 | ARM: Sales Transactions with Posting Discounts > Discounts are immediately recognized upon billing while for non-discount items Create Revenue Plans On = Billing & Revenue Recognition Rule = Default One-Time Direct Posting.
Workarounds provided are:
Option 1: Use a non-inventory or service item to serve as the posting discount. A negative revenue element will be created to record the discount over multiple periods and the other items will retain their Create Revenue Plans On setting. In 2018.1, revenue allocation and reclassification for a negative element in a sales transaction will be supported.
Option 2: Use a non-posting discount. The discount will be implicitly included in the revenue arrangement. The other items will retain their Create Revenue Plans On setting.
Moreover, Per SAID 51421:
When you sell a kit item with auto-expansion, revenue elements are created for the parent kit item and each kit component item. The revenue element for the parent kit item includes the sales amount, but it has no fair value amount. The revenue elements for the kit component items have only fair value amounts and no sales amounts.
The elements of a kit item participate in revenue allocation using the fair values of the kit component elements. Since the parent kit element has zero fair value, its carve out is 100%.
Currently, the ability to have the Carve In and Carve Out amount not be computed independently for the Parent Kit Item and Item Component Item is a system limitation logged under Enhancement #465727 ARM > Kit Items > Auto Expansion for Revenue Management = T > Carve In and Carve Out should not be calculated separately for Parent and Component Kit Item.