AP Invoice linked to Project - Expenditure Item Date for reversed Item line different to Tax line?

We have this scenario, using R12.1.3:

1. Raise REQ in October, linked to Project with Expenditure Item Date of 31-DEC-2021
2. REQ approved, converted to PO
3. AP Invoice matched to PO, Item and Tax Distributions have Expenditure Item Dates also of 31-DEC-2021
4. Validate and Account AP invoice.
5. PRC: Interface Supplier Costs runs and Expenditure Items created against the Project
6. Back in AP, user Discards Invoice Line
7. User matches invoice to PO again, but this time, changes Expenditure Item Date on Item Distribution to today's date of 08-OCT-2021, instead of it being 31-DEC-2021.
8. Validate and Account AP invoice.
9. PRC: Interface Supplier Costs runs and Expenditure Items created against the Project