CO could clear the confusion with two changes. One would be to remove the "window" terminology in the elite benefits descriptions. Your upgrade comes when revenue management says so with ranking in order: displaced etc, instruments, YBM, elite status, ticket price, and time of purchase.

The other would be to use time of purchase in the gate list instead of time of check in. Then the ranking would not be different in those instances when an upgrade is based on the final tie-breaker.