Having a problem with some of the voice command features on the xbox one (although generally plex is already better than Netflix for voice control - so great job there).
It happens for any shows i have where the fourth column is visible on the episode/shows list (so if you have 5/6 episodes or 11/12 episodes) the voice controls only allow you to select items 1 - 6 of the list on the screen (which displays 8) if you have more than just the 4th column (so 13+ episodes) then you can say 'next page' but if you don't you have this fourth column that you can't pick anything from and you need a controller to select the episodes.
One example set of steps to reproduce (and the area I'm seeing it, not for the first time, at the moment):
Set up a TV show
Add 11 episodes to one of the seasons
Use the voice commands to go into the show (even just from the season lists) ("xbox select", "select ")
You'll be able to select episodes 1-6
Go to the next page ("next page")
Try to select episode 11 by voice. You'll find that episodes 5-10 are covered with the 'select 1-6' options, but episode 11 isn't and you can't say "next page" anymore - leaving episode 11 unselectable by voice
hope this information helps but please feel free to get back in touch if I can provide any more info (you may be quicker tweeting me, but I'll set up email notifications to responses to this post).
Many thanks - love the product. Have now become a lifetime member after a few months of trialling this.
Alex