If the stubborn AP is on the network switch like a working one, I suggest doing a Hard Reset
on it. Does the AP pull a DHCP address, such that your laptop on that network can ping it? And
then, check your Master AP access point page and does the new AP ever appear listed there?
Let things go for a little while and does it ever appear there?
Ideas, you can try directly connecting to the stubborn AP with a hard-coded laptop 192.168.0.10
address, and make sure you can see the ConfigureMe-XXYYZZ ssid when it's hard reset? If you
need to re-install the Unleashed firmware, the 18.104.22.168.55 (GA) image is here:https://support.ruckuswireless.com/software/859-unleashed-ap-software-200-1-9-12-55-ga-for-r600
Another idea, is to upgrade your current network, if you have Internet access from your VLAN,
it would try to install 22.214.171.124.47, our latest release. If you block internet access, and can reach
our Support site with your laptop out of network, grab the R600 image from this link's .zip file:https://support.ruckuswireless.com/software/1224-ruckus-unleashed-ap-200-4-9-13-47-ga-software-relea...
Upgrading the current APs to this latest release, might help your stubborn one to be recognized,
or push the same onto it manually, and see if it connects with the others then? Good luck and best