Wireguard split tunneling on GL-iNET openwrt

I recently tried out wireguard and set it up on various Linux boxes, and they seem to do split tunneling by default. Ie I set up the config file on the client with something like
AllowedIPs = 192.168.75.0/24
and the client routes that subnet via the VPN but bypasses the VPN to allow access to the rest of the internet.

But when I set up the GL-iNET AR750 (a WiFi router) for Wireguard similarly, it seems to block all access except to that subnet.

The GL-iNEt router is running openwrt under a proprietary GUI. The openwrt firewall setup looks like it might allow split tunneling, but I don’t have experience with openwrt and I’m hoping I don’t have to experiment randomly.

Does anyone know enough about Wireguard or GL-iNET or openwrt to offer a hint?

I wasn’t able to get split tunneling to work but I did use the VPN Policy option to exclude certain websites from going across the tunnel.