Hi!
I have a similar problem as already reported here. After being away from home for couple of days, when I turned on my LibreELEC on R-Pi 2, the 10 VPN servers configuration within OpenVPN Manager addon was gone. When I tried to configure them again, I started getting error messages about failed authentication. I've tried deleting all config as solorize mentioned above but it didn't help.
(Logon credentials for NordVPN work fine from Windows laptop or Android phone.)
Log attached. Please let me know if I should provide more info.
Version Info
VPN provider: NordVPN
VPN manager for OpenVPN: 4.0.3
LibreELEC: 8.0.1
Kodi: 17.1