One other thing: at hotels where the rooms department is pre-blocking the front desk is trained that they can only upgrade Globalists into holes. They are not allowed to break a block just to get you into a suite - even if across all 3 nights of the stay there are one or more rooms available. So if the app is saying the room is available and the front desk is insisting it's not, that's probably what's going on.

Slightly less likely is they are overselling the standard suite category with the intention of upgrading.

But right there, when you are standing at the desk, if you haven't already been upgraded and the agent can't see a hole on the grid view between all the other blocks they won't upgrade you on arrival. They can ask rooms to move people but if things are tight expect rooms to say no.

That's when you say thank you, step away and call reservations and use your very soon to expire TSU on them . That took 45 mins to confirm as they moved everybody around to make room.