A quick search shows plenty of complaints about connected clients not showing up in the list.  I have one such device.  And oddly it's one of a group of 3 identical devices, and the other two appear in the list.

The device is working, it gets an IP, I can ping it.   The IP was assigned by a DCHP reservation, but no static IP was set in the device itself.  And the same is true for the 2 identical devices which DO show up in the list. 

Previous threads seem to have ended without resolution.  Anything new on this?