Phantom Hosts on Zombie Subnets?

I use B1300 for wireless APs at my home. That home network runs on the 192.168.1.X subnet. I log into one of these, namely 192.168.1.3, then click on Clients and see the attached screenshot.

As far as I know, I haven’t used 192.168.8.X subnet for several months now, so I am surprised to see two “Active Clients” on this list in that subnet, namely 192.168.8.71 and 192.168.8.86.

Why is this Clients screen showing two devices that shouldn’t be on my network, on a subnet that should no longer be alive (a Zombie Subnet?), and further, even if it still exists, it is not supposed to be able to talk to 192.168.1.3?

This is confirmed a bug, AP mode client list is not reliable.