[Alpha layers now black with shadows enabled]

Thank you a ton! I was able to do the light trick and fix it. 

Have you found anywhere that says why this just randomly started happening to people?

[Alpha layers now black with shadows enabled]

This morning I switched from viewer 2 to Kirstens to see if it was less glitchy with shadows and taking photos.  I quickly noticed that all the alpha layers in my hair (regardless of the hair) were black.  Took a friend's advice and tried turning deferred/nondeferred rendering off/on and it didn't solve the problem. When I turn shadows off the problem resolves itself.  I switched back to viewer 2 and now I'm having the same issue there.  I'm using the most updated versions and have been the past few days and was not experiencing this issue yesterday.  Any suggestions on how to fix this?

 

Photo of the difference