Plex stretching vertically

I have a Plex server with movies that I've ripped. The movies play just fine on my phones, tablets and via Chromecast. When I play movies that are 2.35:1 ratio (wide screen) I expect a black bar on the top and bottom. However, when I use Plex on Tivo it stretches the picture vertically to fill the screen. This makes circles look oval and people get tall and skinny.

Is there a setting to fix this on either the Plex server or on the Tivo itself?