When I try to enter full sceen mode, the photo isn't any bigger than it is in loupe view. Am I missing something? Do I have something checked that is limiting the size of the photo? Why isn't this working?
Does this happen for all images? What is the resolution of your image and what is the resolution of your screen? Lightroom will only show your image as 1:1 so it's low resolution, it will appear small on your screen.