Switching audio/video tracks resets the subtitles to default

Please fill out the following template so we can reproduce and fix your issue as quickly as possible!

Environment:
- Preview version: all
- Browser name and version: all
- Operating system and version: all

Steps to reproduce the problem:
1. Play a video with multiple subtitle tracks
2. Select an alternate subtitle track
3. Select a different video quality or audio track.
4. See that the subtitles revert back to what they were before.

What is the expected behavior? (Screenshots can be helpful here)
Subtitles should be unaffected by change in video/audio track

What went wrong? (Screenshots can be helpful here)
Subtitles change. For example, if I was on originally english subtitles, and then select french subtitles, switching audio track or video quality resets to english subtitles again. I'm not sure if this is because it was the previous language, or if it's the default language, or if it's the first language in the menu. The menu will still say French in this case, but the subtitles shown will actually be English. Need to investigate more.

If relevant, link to file (or attach file here):
https://cloud.box.com/s/8v69y8k7awf7re56awe9d6lqf5zx56ut