VPN up but no traffic flowing after changing the WAN interface

Before making any changes, I have a Fortigate (5.4.10) to Fortigate VPN working fine. I created the VPN using the wizard.   Have now added a second WAN interface to one of the Fortigates with default static route with a lower priority so normal traffic does not use the new WAN interface.   I want to use the new WAN interface exclusively for the VPN. So I modified one end of the VPN connection to use the new WAN interface and modified the other end of the connection to use the gateway of the new WAN interface. The new VPN comes up fine, but no traffic is passed through.   Any ideas what is wrong or how I can debug this?   I tried a policy route to try to force traffic for the remote network to go out the new WAN interface, but that did not work.   Thanks