I don't have MX so can't tell for sure, but could it be the status of the firmware? 16.16 is current, so it doesn't show an update. But 16.16.2 is a beta, so it shows there is an newer beta?
(again, can't tell since I don't have MX, but check if this is the case in Firmware Upgrades -> Overview)
Esteban J Nunez
School and Church