Hi everyone, I discovered that my addon BeQuiet has been breaking this seemingly due to a race condition. I’ve submitted an update to curse which will delay the mute by 1 frame however you still should not hear audio and this will prevent dialog from breaking. If you use a different addon to mute talking heads please inform your addon author. I have an update pending review on curseforge.
https://www.curseforge.com/wow/addons/bequiet
https://us.forums.blizzard.com/en/wow/t/talkingheadframecloseimmediately-breaking-npc-dialog/1554881/6