thumbnail & icon problems.

[Cumberiron]

By default Hybrid uses Mp4Box for muxing and support settings a cover art.
Can't really say more since you didn't even care to share the container you used.
I doubt this is related to NVEncC or Hybrid, my guess is that the parser used by Windows has a problem with one of the settings you used.

Cu Selur

Hello Selur!
I use MP4 and MKV containers always. But using mkv or mp4 containers with Hybrid's NVENCC seems indifferent regarding to the icon problems. However Hybrid FFMPEG NVENC has no such problem with the same encoding settings. Staxrip has no icon problems, despite it uses Rigaya NVENCC with the same encoding settings.