This issue is present in Plex Android TV version 7.27.0.15018. The background for this topic can be found here.
No need for a new thread. Just continue with the old one.
Edit - Since this is a beta issue. I’m reopening it.
This issue persists in Android TV version 7.28.0.15170-beta
Oh sorry. For some reason I thought this was mobile beta, which is why I closed the thread originally. Didn’t pay attention that this was Android TV. The playback speed modifier has not been implemented yet for Android TV. The music player UI will be getting an update like mobile to include newer music features like playback speed and sweet fades. There is no point in bringing this up for each update since it may be a while before it’s ready, so I’m going to close this thread, again. You can create a feature request if you want to track when the feature is available.
