I'm using LR 4.1. When in survey mode, if I select an image and hit Z the resulting 1:1 image is not sharp. If I zoom in or out and back to 1:1 it becomes sharp. This is not a problem in Loupe mode. It's not a delay issue - it never becomes sharp unless I change the zoom level. I have 1:1 and standard previews pre-generated.
As are as I know, I didn't have 1:1 previews for this image. I know I wasn't in Loupe at 1:1 with this image in this session either. When I first went into Survey mode and zoomed to 1:1 the image was pixelated, but I had the "Loading..." message appear at the bottom. After about 5 seconds the 1:1 preview was built and displayed the sharp image.
Europe, Middle East and Africa