Yes familiar with the Plex Dance - haven’t had to do it in years though 
Strange as it might I was correct is Plex Movie Scanner / Plex Movie.
This was the default setting for a new library as the only thing I tend to look for is removing the prefer local media exactly due to past problems.
By the way there is no Plex Movie choice as a scanner so it appears that Nvidia Shield did not yet get the new scanner implemented.
