I don't have this issue, but use Relive for any recording with the AMD 390X not an Nvidia tool.
As a matter of fact, I recorded this on an AMD 1800X and had no issues with the recording. It is not 120FPS, because my screen can only do 60fps and I usually record 30fps but looks good to me
Are you using ShadowPlay? If so, you'll need to report it to NVidia.