Ok, this has happened to me twice in one month so I thought I'd share in case it helps someone else out. I buy first class (business - generally I fares) tickets when flying domestically. Twice I tried to go standby on an earlier flight. The first time I was passed over by an upgrade. I asked how that could be as I had a first ticket. Initial response was that I was upgrading and would be behind everyone else who was originally booked on the flight. When someone finally listened and looked at my ticket they apologized and said I was listed incorrectly as a RV1 instead of RF1. For that flight it was to late as they wouldn't un-upgrade someone and I wasn't going to push the issue.

Fast forward a week and I'm standby again for an earlier flight and I ask the agent what my chances are and he responds not good. Fool me once... I ask if I am listed as RF1 or RV1 and he responds RV1! I say can you change it to RF1 and he had to ask a colleague for clarification as he too thought I was upgrading! Supervisor says yes list him as RF1! Too late, passenger WOO, T who was listed correctly had cleared before my listing was corrected. So OK, I enjoyed the steak frite and Krug in the First dining while waiting for my original flight.

In the first case a check in agent listed me for standby and in the second case it was via the AA app. Bottom line, based on my experience, if you are standing by on a paid first ticket make sure you are listed correctly RF1 not RV1.