Downgrade after upgrade?
 

On a HKG to TPE flight and was refreshing my mobile boarding pass before the flight. I saw I got upgraded to PEY which was nice, but right before boarding I got downgraded back to economy again. I asked the crew what happened and they told me that someone with the same status as me (gold) decided to buy an upgrade at the last minute and that I was downgraded back to my original seat. Once I was to board, I actually got bumped up to PEY again. Now I’m not complaining since I eventually did get the upgrade but more out of curiosity, can they downgrade you for reasons like this? Also, what the staff told me was obviously a lie if I managed to get the upgrade in the end.

How do you know it was a lie? Maybe someone cancelled their trip or didn’t show up.

I don't see why not. It would be annoying as a passenger and not impress one with the airline, but if you bought an economy ticket then there's no obligation to give you an upgrade. Saying you have it then taking it away isn't a smooth way to handle things, but it seems within the airline's rights.

I always ask the lounge receptionist to print out the BP for me when I get an op-up.

Was the first PEY seat you saw on mobile BP and the one you eventually sat on onboard the same?
How you know its a lie???

They've done this to me. Without the final upgrade. I can assure you, it's possible and hugely depressing. I prefer not to be upgraded at all than go up and then down!