Besides the problem that the backup doesn't work (I have alle the permissions and tried another folder) I have the problem that the develop module doesn't work. It won't even show a preview.
The problems started after the lastest update.......
Do you get any error messages?
Try to deactivate the GPU support: Preferences -> Performance -> Uncheck GPU, then restart Lightroom.
This would help on several machines.
Anotherpoint could be a corrupt monitor profile.
Photos appear as black, gray, or blank rectangles in Lightroom
Thank you Axel, the latest updates fixed the issues...
Retrieving data ...