Sorry for the Export issue.
As if now all i can suggest you is to roll back to the previous version, please check this link on how to do that - Roll back to a prior update version
What is it like if you turn off OpenGL support?
Tried that, Open GL is actually turned of at the moment. No difference what so ever.
There are some well reported issues with crashes and lockups on Mac OS X El capitan with LR 2015.2.1 that aren't helped by turning off graphics card acceleration or the "add photos screen"(another source of lockups). Only solution at the moment is to roll back to 2015.1.1 using the instructions given above by rpandita.
So i did. Now running Lightroom-version: CC 2015 .It works!