I was having an issue with the gong at Xuen. When I would click it, I would phase as expected. Wrathion would stand there, friendly, and the RP would never start. I abandoned the quest, picked it back up, and went straight to the gong without talking to Wrathion first. Everything worked as intended then, and I got credit for talking to Xuen in the same stroke. I can confirm that this worked for another player who was having the same issue that I was. I cannot confirm whether this works for other gongs.
Another issue people are having a lot is at the Temple of the Jade Serpent, with speaking to Yu’lon to get his blessing. In this case it isn’t usually a bug. You have to exit the temple and go out beyond the instance entrance, all the way across the bridge. There is another spawn of Wrathion there that you have to talk to. That starts a cutscene where you get the credit for talking to Yu’lon.
Hopefully this helps somebody.