I have no issues at all on my system. (MacBook Pro 15 inch + retina, NVIDIA GPU, macOS Sierra)
You can try resetting Mathematica to its default configuration. Here is a link to the tech support article with the details:
Resetting Mathematica
Cutting to the chase, the first thing to do is to hold down the option and shift keys while double-clicking the Mathematica Icon in the Applications folder. If this doesn't work, you can delete (move to a safe place) the user libraries as described in the article.
If this does not work, then a complete re-install may be necessary -- what version of the macOS are you running?