When a discount is added to a project purchase order with a posting profile main account, other than the main account of the item used, the discount is ignored in the consumption of the related project budget.
This idea is to ensure that the discount is taken into consideration when consuming the project budget to prevent a data inconsistency between the project budget and actual spend.
An example of a scenario that is happening now: A purchase order with a line of 1250 dollar and a discount of 250 dollar (total of line is 1000) is consuming 1250 dollar from the budget while the actual spend on the project is 1000 (and correct). In this case, the idea is that the consumed budget should be identical to the total amount of the purchase order, taking the discount into consideration.

Administrator on 5/6/2019 2:17:30 PM
Thank you for your feedback. This is a great suggestion! We will consider this in our roadmap.
Sincerely,
Kim Nelson
Program Manager, Microsoft