I have recently downloaded version 5.4. Opening LR, I no longer can zoom in by clicking on a "magnifying lens" over a picture segment, which was extremely helpful to see noise levels and color distortions while editing. Instead I can zoom in to what now appears as a heavily pixelated enlarged image, which does not show degree of focus and sharpness. Have I opened my libraries in a new format? How can I get back to the preferred zoom feature (which was available in 5.3)?
Clicking in an image or using the space bar switches to/between the last zoom settings. You may have to select a new zoom ratio just above the Navigator window.