I'm still running 2010, so I have no direct experience of 2012, but I really doubt that such a basic function was dropped. I suspect that you have a bad installation.
I noticed this. It's a drag. Try RMB
Welcome to SolidWorks forums Stuart.
I can see the same behavior here but as Roland suggested, right click copy and right click paste is working. Agree with you that this was/is a robust option and should be back.
You might also find this post helpful for your future reference.