Images in develop pane not rendering - LR 14.5.1

I've got a new problem with images not rendering in the develop pane in Lightroom 14.5.1.

The images look like they are out of focus effectively, every single one. I can elave the sceen for long periods of time (half an hour) and the image doesn't render at all, it still looks just out of focus. 

The only way to get each image to render is to zoom in to 100% then back out again, which is a real pain. Move to the next image and then back to the previous one and it is blurry again. 

I've rendered smart previews, standard previews, 1:1 previews, nothing makes any difference. 

Using an M3 mac with 1gb free space on the drive and 32gb memory.

I've also tried optimising the catalog, and trying a new test catalog, all the same. 

Before anyone asks, yes, the images are definitiely in focus.

Any ideas?