I have recently experienced that Lightroom crashes and behaves oddly when I switch to crop mode (never in any other mode). Sometimes, instead of showing the image, it just shows a black image. Sometimes, Lightroom just stops working and my Mac freezes completely. Then I have to restart my Mac. And sometimes I get weird looking behaviour which is illustrated in the image below. The pattern can change depending on where I have the mouse.
Its probably a bug that developers need to fix, but I just want to report this behaviour - maybe someone else experience the same?
First thing to do is turn off the GPU option on the performance tab of the LR preferences.
Thanks for the advice. After a few days of trying without GPU activated, it seems to perform better.