I've not yet been downgraded from an app shown upgrade. I've actually seen it a couple times know where I am upgraded at 24-48 hours before hand, and then upgraded again the morning of.

Bait and switch is a bit strong though. No way does anyone bother to do this just to try to entice you not to drop last minute. They probably don't even think about you checking in on it. I suppose Hyatt should go back to never showing you the pre-placement into the upgraded space to begin with.

But, I will affirm the opinion that too many globs are in the system making upgrade at check-in space too limited. I don't know how many glob-lites were minted last year, but it was ridiculously easy for US-based casual travelers to quality last year between double credit promos, half nights needed etc.