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
Thank you for that, I'll look at that but I found one photo that was edited that was causing the problem, I removed it and it worked fine. Kind of strange
Sorry about that, I couldn't find it after I posted it.