With Easy Mesh via an AXE75 and two RE715X extenders, I occasionally see a phantom "satellite" with a name like:

 "proxy_mac": "B0-A7-B9-64-F2-D9", "connection_type": "2.4GHz", 

The device is highlighted because it isn't found. 
 

Any clues as to what causes this? This seems separate from the proxy macs that are assigned to clients since it is showing as a satellite with (potentially) connected clients of its own.