I recently encountered a problem with OpenVpn and the riseup VPN on a friend's notebook. Although it connected and seemed to work none of the traffic was going over the RiseupVPN.
This is the configuration of the .ovpn file that did the trick for me. Save it under C:\Program Files\OpenVPN\config\RiseupVpn.ovpn.
Or alternatively download the file here: https://drive.google.com/file/d/0B06EJahqJCOCOVV2NERwNEtVRlE/edit?usp=sharing
Also, make sure to run OpenVpn as administrator. Right click on the OpenVPN application >> choose “Run as Administrator"