This problem is difficult to even describe. Mid work session my cursor stops working on the left side of the screen. I'm in full screen mode and my cursor shows up, say over the folders or images on the left side of the screen but when I click I get nothing. If I have an image, in grid view, selected on the right side of the screen I can use the arrow keys to move around the grid, anywhere, but the cursor will not click/select anything.
I can then quit LR, restart, and everything is back to normal. Problem solved until some point when the problem returns. I can't isolate what triggers the problem. Possibly after I've been away from the computer for a while and return with LR still open.
Macbook Pro 2011
LR-CC (latest version though this has been a problem since at least LR-4)