Copy and Paste Selection in Gimp is copying empty space, instead of image?
Be sure you are selecting the layer with the image, because if for any reason there is another layer (maybe you could have created accidentally) and this layer is not in the area you are selecting, it could seems to you like an empty transparent layer.
In this case, delete this layer and use this from another superuser answer: How do I use the Selection tool to move things in GIMP?
I'm having this issue too with Gimp 2.8.10 on OSX. Seems like a bug. Quitting the program and restarting it solved it for me. Merely closing and re-opening the image wasn't enough.
Same thing happened to me, the non-Python build is broken on OSX. You have to install the one with the extras, current link is http://gimp.lisanet.de/Website/Download.html .