Answer

The PTZ cameras use a different detection mechanism from other Q-SYS devices. In order to see them, the PC running Designer must be in the same IP range as the cameras.

By default, the cameras are set to get a dynamic IP address. If there is a DHCP server on the network, they will get an IP from it. It not, they fall back to a link-local IP address in the range 169.254.x.x.

Simply change the IP of the PC running Designer to get a dynamic IP address. This will put the PC in the same range as the camera. Restart QSC Designer and open Configurator. The cameras should now be visible and their IP configuration can now be changed (if required) to match the rest of the system.