@bcopeland has also indicated that even a mains powered device that is properly connected can also temporarily show no routing - I've seen it one of my C7 hubs, with both a range extender (Aeotec) and a wall-wart plug (Jasco). Usually a simple reboot would re-populate the routing info, but it could disappear again. The function of the device was alway fine, even when no routing showed.
Unfortunately I cannot remember his explantion accurately, and don't want to badly mis-quote him here. Ahh...here it is:
Ahh...here it is:
