This has happened for three different trips now and on one trip three of the six segments. I had selected seats when I booked the tickets. Those seats are gone and it shows I don't have an assigned seat or has moved us back to normal seats. I go into the flight (tried in the app and computer) and select new seats. Everything goes fine and click through to where it confirms the seats. It then says unable to confirm these seats and that they might have been taken during the process. I try again and continually get that error. I've called and the agent has fixed the seats a couple of times but it's happened again and I'm getting sick of having to call. Anyone know what the deal is?