I'm sure there's probably a thread on this somewhere, but have you noticed that having a pet in cabin notation on your reservation means your name never actually gets to the upgrade waitlist (even though you are "upgrade waitlisted")? That means that you get skipped over by literally everyone else whose name actually makes it to the waitlist itself. It's a thing as confirmed this past weekend on a trip. The pet in cabin notation prevented both the outbound and return flights (MR-style to pick up a new kitten) from upgrading. Thankfully, AS employees are excellent as always and went ahead and upgraded me as my place on the waitlist had been skipped over.

Have you experienced this?