Explicitly designed to make it impossible to use a suite upgrade since DSU are only 7 nights. I would call MHC if you have one and explain, give the dates and insist they book the room and apply the upgrade. I've had luck in the past in a similar situation but who knows anymore with how customer unfriendly and apologist for hotel abuses Hyatt has become. Not sure why they don't just tell Hyatt, hey add us to the fake BS made up list of places that get to just ignore and opt out of benefits like suite upgrades. I mean Hyatt lets tons of other properties do it, so I'm sure they would let them instead of currently making them go to the extra trouble to game the system.