Picking Rule using Locator Receipt Date

I'm testing picking items that are in multiple locators to pick the one with the lowest/earliest receipt date, so I have a picking rule with Subinventory ASC = 1, Locator Receipt Date ASC = 2.

In testing, I noticed that when an item has both PO Receipt and Subinventory Transfer material transactions against it, the Subinventory Transfer seems to take precedence, i.e., the earliest SubInv Transfer location got picked rather than a much earlier PO receipt for the same item into a different locator.

Example: Item 1234567 PO Receipts into locator 15-43-K, 2/28/11 (4 units), 4/21/11 (3 units), & 7/28/11 (1 unit).

Same item has a Subinv Transfer on 12/11/2018 into 40-07-C (4 transferred from 15-43-K)