Welcome to FlyerTalk!
Unfortunately, your foundational knowledge of upgrade space is a bit incorrect (PN is reserved for Global Services upgrade space, not general members).

Read thought these wikis for a better understanding about how MUA upgrades and waitlists work and then come back here to ask any follow up questions.
https://www.flyertalk.com/forum/unit...de-united.html
Understanding the United Upgrade List Comprehensively
[Consolidated] Chance of upgrade clearing on my flight