HLS Subtitles with external VTT out of sync

[WINOFFRG]

Have you read the FAQ and checked for duplicate open issues?
Yes

What version of Shaka Player are you using?
4.3.8

Can you reproduce the issue with our latest release version?
Yes

Can you reproduce the issue with the latest code from main?
Yes

Are you using the demo app or your own custom app?
Both

If custom app, can you reproduce the issue using our demo app?
Yes

What browser and OS are you using?
Chrome, Windows 11

For embedded devices (smart TVs, etc.), what model and firmware version are you using?

What are the manifest and license server URIs?

Manifest: https://stream.mux.com/VZtzUzGRv02OhRnZCxcNg49OilvolTqdnFLEqBsTwaxU.m3u8
WebVTT: https://www.vidstack.io/media/sprite-fight.vtt

What configuration are you using? What is the output of player.getConfiguration()?

Default Config

What did you do?

$('video').ui.player_.load('https://stream.mux.com/VZtzUzGRv02OhRnZCxcNg49OilvolTqdnFLEqBsTwaxU.m3u8')
await $('video').ui.player_.addTextTrackAsync('https://www.vidstack.io/media/sprite-fight.vtt', 'en')

1. Select English Track
2. Seek to a time, Found captions out of sync

What did you expect to happen?
Captions should have been in sync, I have checked the timestamps in VTT they are correct.

What actually happened?

Captions are out of sync on both native video element as well as on UITextDisplayer

[avelad]

I'm working on a fix for it!