My entire team has on uptime. It's a basic monitoring item, right? I've seen other people reference making a wish. At this point, I am left to assume that Meraki does not wish to directly share this information, any more than they wish to share CPU/memory usage directly.
Almost seems like Meraki is embarrassed to show the uptime on these devices. I have a monthly Make a Wish reminder on my calendar. I Make a Wish for MX features: uptime, interface stats including errors, scheduled reboot, improved templates that do not require re-entering VLAN addressing information, a fail over feature or disable WAN1 even on devices with single dedicated Internet port such as MX60 and MX64 if WAN2 is setup and in ready status. Uptime and errors can be attained by calling in and their is an SMNP OID for port errors, but you have to use additional software from Netreo or SolarWinds to get this information. My $35 Arris modem that I bought at Walmart displays the CPE uptime and it is on the device, but just needs to be displayed.