This issue is still happening. I have tried all the major available apps to do face mocap on the iphone now. They all have the problem of both eyebrows moving at once. We are using iphone 15 PM It has been 2 years with no response from Apple on this?? I guess apple has given up on face capture. Our company had been testing the iphone to see if we could do mocap with it. This problem makes iphone unsuitable for our professional mocap needs.. We will have to look for a different face mocap solution