Subnet not saving for OPT1 interface

[JackTripper]

i put a 3rd network card into the router, and it's now up as OPT1.

Under its IP Configuration i try to set the
IP Address: 192.168.2.1 / 24
with Bridge: None

i save the changes, apply, and go back to it and the values are cleared.

My LAN is
IP Address: 192.168.1.1 / 24

Is there some concept that i'm missing and the router is intentionally clearing the values? Can i not have a second LAN card on another subnet?