I tried to find out more about these issues on the Plex forum, but there aren't many Vizio users, it seems. I have basically given up on the app. I let my wife and kids use it when they want to watch a show and I'm too lazy to turn on the PC. For anything I watch, I use KODI as the front-end and MPC-HC with madVR as the player/renderer. Plex is awesome for remote streaming, though. I wouldn't get my hopes up on this ever getting fixed on our outdated platform (Opera).
Synology DS1813+ & DX513 x2
X-Rite i1Display Pro, ArgyllCMS, DisplayCAL, madVR, HCFR
HTPC running Kodi with MPC-HC + madVR, Plex for remote streaming