I switched to LibreElec from OpenElec about six month's or so ago. Ever since switching, I've had audio/video sync issues when watching live TV via NextPVR. I use a mix of RPi2 and RPi3 devices. It doesn't matter which pi I'm using, over a period of time, when streaming live TV, the audio and video get out of sync. All of my pi's are properly MPEG licensed.
I never had this issue with OpenElec, only with LibreElec. This and a few other issues that I've been experiencing are making me think that I need to switch to OSMC or something else. One of those other issues is the TV guide not progressing or scrolling when the TV is off and left on the guide. I have to exit completely out of the guide and get back in to get the latest guide listings. I was once told that is a Kodi issue, not a LibreElec issue. But again, I never had that issue with OpenElec.
I can live with the guide issue, but the audio/video sync issue is something that is becoming a major issue for me, and I'm ready to dump LibreElec. And as I said, this is not just one pi experiencing the issue, its all of them.