Hi, I just thought I’d share here what I’ve experienced, maybe it helps someone else get up and going. After installing Rack 2 and starting it, nothing would happen… the process was there but no window. Logs showed that it was hung somewhere loading ASIO drivers. The VST, however did load within Bitwig. I’ve got a focusrite ASIO driver, a Native Instruments ASIO driver for my MK3 and have Jack2 installed.
I started Jack up thinking maybe if jack was running, then Rack would be able to load that driver. I saw that Jack would no longer load up, just hung with a white window…
So I uninstalled Jack.
Then I tried Rack again, without any rebooting, and voila it worked 
Out of curiosity, I then reinstalled Jack, it is working again as well, Rack is still working, all my ASIO drivers are now getting along
So I guess, If you have Jack installed, uninstall it, then install rack, then reinstall Jack.
Enjoy!