I was able to track the device down by going System Manager > Configure > tags > enrollment type > Android fully managed.  I have a tag I've been using for the tablets and noticed it was missing.  This didn't solve the device being absent from the System Manager > Monitor > devices, but at least I was able to find it.  ... View more

Didn't you set a password in the dashboard? https://documentation.meraki.com/General_Administration/Tools_and_Troubleshooting/Using_the_Cisco_Meraki_Device_Local_Status_Page#Changing_Log-In_Credentials ... View more