I've been getting intermittent lip-sync issues when playing blu-rays on Xbox One. At first I thought it was only on certain discs but I actually seem to have the issue intermittently even on the same discs (as in I have the issue when I first play a disc but then it seems to improve, then it can appear to go out of sync again).
I've tried lot of different combinations of steps: Trying different discs, different audio output (stereo, 5.1, etc), loading the disc straight from a fresh start-up vs. loading it after playing a game or another app, skipping around the disc to different chapters, pausing, fast-forwarding, etc, but I haven't been able to find any consistent reproduction of steps. Sometimes the lag is there, sometimes it isn't (or at least less so).
My television is a Panasonic ST60 with the latest firmware. The lag isn't present when I play the audio through the speakers, but I like to play with headphones. The only audio out from the TV is optical, so I'm using optical out from the TV to a cheap optical to analogue converter (like this: http://amzn.to/1fAV5PP), which then goes to a cheap pair of dollar store PC speakers, which I then plug my headphones into (just regular Panasonic stereo headphones). It's a messy audio setup, I know, but it was the cheapest way to connect headphones to the TV with volume control.
Normally I'd blame the messy audio setup, but I don't have any of these lag issues on my PS3 or PS4 blu-ray playback, and I don't seem to have the issues on Xbox One Netflix or Xbox One games.
Any help you could give would be appreciated.