I switched my project over to new beta versions of iOS 10 and XCode 8. In all three areas of my app where I use:
imageView.layer.cornerRadius = imageView.fra
This problem also happened to me.
I moved these code imageView.layer.cornerRadius = imageView.frame.size.width/2 from - (void)awakeFromNib to - (void)drawRect:(CGRect)rect and this problem went away.
My imageView is sized by autolayout. I think that height and width are not decided when awaking from nib on iOS 10.