Captive Portal docs - Unable to add new interface in step 1?

[syutbai]

Hi,

I'm trying to follow the docs for setting up Captive Portal, located here:  https://docs.opnsense.org/manual/how-tos/guestnet.html .

Step 1 says to configure a new interface, but I cannot find the + button to add a new interface.

I already have a LAN, WAN, and Wireguard interface, but it won't let me add a new one for the GuestNET.

My current OPNSense version is 20.1.7.  Is there something different in the new release? 

Thanks,
syutbai