[VRChat v2018.4.1p1, build 652] I've noticed a pattern with my audio on some avatars in this latest update. Any avatar with over 3 audio sources will, well, not have any audio playing, either that or the first 1/10th of a second or fail to activate at all. Now for material animations, they do not show up in mirrors. You will see that I turned on Holoport many times during this recording, that is because I was showing my faces have different emotes using separate materials during gestures.
This video will show you the issues in practice, though I assume the video quality and audio quality is really bad due to me not having OBS set up properly, as I had no need until now.