On a recent flight from SAT back to SEA, I got an email noting the flight was oversold and AS was looking for volunteers. I clicked the buttons and was then put "on the list." Got to the airport and checked in (I had a bag) and asked the agent who told me she had no idea where I was on the list and if I'd get bumped. I went to the gate and asked the GA who also had no idea. After asking in a different way, I was told the flight was not actually oversold and no volunteers were needed. I wasn't getting an upgrade to begin with, but if I hadn't been proactive in asking, I'd have been standing at the podium until boarding was complete, waiting to hear. They seem to have a broken system.