I use OpenVPN in Fedora 30 using the Network-Manager. No applets I have never gotten them to work right. I was only able to get NordVPN working on Fedora by manually inserting the information from the .ovpn file. I couldn't even import the .ovpn file on Fedora without having to do so manually with this command:
sudo nmcli connection import type openvpn file nordvpn-server.ovpn
I didn't have any of these problems on Solus. I run Budgie on my other laptop and it imported from the .ovpn file on both my Laptop and my roomates Desktop.
It's weird that the original poster and I are both having the same situation with NordVPN connection failure. Maybe it is an issue with NordVPN and not either of the distros discussed here.