Gen 1 FireTV External VTT or SRT Subs not rendering

[enduser]

Server Version#: Latest Beta channel update as of Oct 25 2020
Player Version#: Latest on Fire TV for my device Gen 1 Fire TV box (auto update)

I have external SRT and VTT subs for some foreign media that renders fine on the Shield, AFTV Gen2, Android mobile, FTV Stick. However, the First Gen Fire TV box doesn’t like to render the subtitles.

I checked settings, using latest Movie Player, ensured the subs preferences match what I have set on the Gen 2 box, but they still wont render. I tried reinstalling the plex app, deleting cache, checking device settings… I see other posts having similar issues, but don’t know if it’s device specific.

[enduser]

Now VTT subs no longer work in Plex web or Plex on Tivo stream dongle thing.

SRT subs appear to work in Plex web at least.

[enduser]

I removed some of the “optional” timestamp from the VTT file, and now its at least working for web.