I shall not be surprised if the policy and procedure have changed. I am unfamiliar with TG's ROP but most other North American *A programmes have "capacity control" on this sort of upgrade request and is generally not based on physical availability. AC for example, actually converts to a different booking class ("R") for business class upgrade from economy. So if you're booked in Y class and you want to upgrade to business, it's not based on the availability for sale in the usual C/J/D/Z business buckets, but based on R availability, the upgrade category and a subset within the business class category similar to I (business reward). C availability may be 9 but revenue control can "zero out" R = 0, you won't be able to upgrade although there may be seats available for sale in business class. (AC does not have first class.) In those situations, as with most North American airlines, you will be waitlisted for upgrade. If there are any unsold seats when the flight closes, you will be give the seat at the gate. The process is affectionately called "aero lottery" by those North American flyers. Of course, if R > 0 when you request, you will get your upgrade immediately. It's an unknown and often frustrating variable.