Hi everyone, so our upcoming UA flight from LAX to LAS was a regular economy fair,> Later, I paid for E+ plus. I have been considering to upgrading to F, and under reservations it was saying that it was available for $80+ under the main tab with seat sections but when I go to select a seat, it says online upgrades are not available even though it's still showing many open seats. Is there a reason for this? I'm thinking they might be holding them for passengers with status? The flight is on Monday. Am I doing something wrong? I know there there is a separate thread about upgrades, do I need to wait until tomorrow (the 24 hour window) and check in first before the release the seats ?