I am new to Lightroom (and this forum). I have imported about 350 photos from various sources: email attachments, share sites, my camera, and my iPhone. For some photographs, Loupe View works fine. For other photographs, the image I get in Fit is way smaller than the preview area, and the image does not respond to Fill at all, it just stays the same. I'd be grateful for an explanation and a solution.
Fit and Fill only resize smaller to fit or fill the Loupe area. If your image is already small enough to fit in the Loupe area w/o shrinking then it remains at 100% zoom. It’s a way to tell your images are small/low-resolution, I guess.
If you want to see the image bigger than 100% then you have to actually zoom in more using the Zoom slider, which you can enable the visibility of using the arrowhead/triangle at the lower-right of the toolbar and putting a checkmark next to the word Zoom.