I have heard of some returning to battery issues from several people and also slide not locking back on the last round, and a possible front sigh issue. Do we know if Sig has addressed these now?

The front sight issue was taken care. New pistols come with an xray front sight and pistols released with standard night sights,SIG will replace the front sight with an xray sight upon notification.

The slide may not lock back on an empty mag if your thumb is resting on the slide release, or your thumb is rubbing against the slide. I have experienced the thumb on the slide release and a friend experienced the thumbs rubbing against the slide. Both of these issues are shooter error.

The most common reason for a SIG malfunction is a very dirty or improperly lubricated weapon.

I had the slide lock back issues. It was 100% a high-thumb grip problem.