Even the traceroute looks ok, ......
If already added vtun0 in the DNS Forwarding, listen-interface, I'd remove the opendns DNS server
delete openvpn-option "--push dhcp-option DNS 208.67 ..................."
set openvpn-option "--push dhcp-option DNS 192.168.100.1"
commit
save
Connect to the VPN, and from the client, try
nslookup google.com
Did you try by using the 'Packet Capture' ?
And, if still not funcioning, could you post your sanitized config ( use the 'spoiler tag', code and then paste) ?