I hadn't seen that model before. When I look at how it's configured in the gui I'm not sure exactly what it's doing. Can you do a traceroute to the network that works, and see what hops are present?
It also just hit me that you might want to look at the router, or layer 3 switch that has the gateway for the 172.12.30.0 network to make sure it has a route to the 172.31.32.120 network.
I'm going to make some assumptions, but you can change the command based on what you have. You might need to change the subnet mask and the tunnel interface number, but you can point a static route out an interface. You could also use dynamic routi...