4.8.4.0-v2 and 4.8.5.0 (which in theory are the same) there's something that's still not working (or it might be an issue with the Windows Emby Theater app).
Trying to do this:
It hangs on Windows Emby Theater app (Emby for Windows 1.1.553.0), even though it shows as playing (with the timer advancing) on the Dashboard:
It has no issues playing on Edge (also direct play) or Firefox (transcode), so I'm not sure if it may have to do with the Windows App or the 4.8.4.0+ up