Route Error when Switching from TAP to TUN

[volleynbike]

We have a Server-Client setup. On a Windows 10 client, I am testing 2.6.5 changing from --dev-node TAP_Win32 to --windows-driver wintun. When i switched to wintun there was no traffic going through the tunnel. 'Route Print' shows why:
With TAP_Win32
Active Routes:
Network Destination Netmask Gateway Interface Metric
192.168.100.0 255.255.255.0 10.10.0.1 10.10.0.50 21 (10.10.0.50 is dhcp assigned from Server for TAP_Win32)

With wintun
Active Routes:
Network Destination Netmask Gateway Interface Metric
192.168.100.0 255.255.255.0 10.10.0.1 10.5.1.16 21 (10.5.1.16 is static ip of the physical ethernet interface)

If i manually delete the above and add the correct route (as under TAP_Win32) then everything works. Why does activating wintun cause the wrong interface to be assigned to the route? Is this a bug? Is there something i can change in the ovpn file to fix it?