I have an issue with FaceTime on my 2011 iMac. Called my sister in the US on FaceTime and encountered this problem. When I connect, I get her in the main window. My own image in the top left of the FaceTime screen is a static image. On her side my image doesn't show at all. Either when she is using her MacBook Air or her iPad. Voice is OK If I try the same from my MacBook Air this end all works fine. It was working OK on my iMac on EL Capitan. Don't know if I have missed some setting or something unique when trying to connect from a 2011 iMac.