I just recently purchased Lightroom 6. I imported several photos but when I enter into the develop mode, all I see is a blue screen.
Edit/Preferences/Performance and uncheck "Use Graphic Processor
Deactivate the GPU acceleration https://helpx.adobe.com/lightroom/kb/lightroom-gpu-faq.html
You may also try it it helps to upgrade your graphic driver first. If you have an AMD GPU, make sure to use the latest beta driver.