Have you tried disabling GPU acceleration? Let us know if that makes a difference.
Edit >> Preferences >> Performance (tab)
Lightroom >> Preferences >> Performance (tab) on Mac OS
Uncheck the box “Use Graphics Processor”
Then click OK
I actually have tried to do that, but the preferences window stops responding when I click the Use Graphics Processor box.
I was able to follow the instructions to do it manually. It helped fix the problem. Thank you so much I can finally use the new Lightroom now!