Looks like a problem with the hardware acceleration communication with your video card.
menu / edit / preferences / performance
Uncheck the "use graphics processor" box.
Thank you so much! It worked and now I can see the actual picture! Thank you!
What version of the mac OS are your running?
What exact version of Lightroom are you running?
The GPU option is only available in Lightroom 6 and Lightroom CC. If you are using an older version that option will not be there.
Mac OS Sierra 10.12.1
Lightroom 4.3 64 bit
The only solution is to upgrade the Lightroom version?
Thank you for your answers
You have a different problem than the original poster.
If the problem is dark/clipped shadows, see this thread: Re: Something wrong with the develop mode.
If you want to stay with Sierra, you will need to upgrade to LR6 to fix the problem.