When I import photos to Lightroom 4.1 not all of the images get imported if they are a mixture of file types. All of the images get moved to my folder where the images should be, but they do not get added to lightroom.
I had a mixture of JPG, TIFF/PSD files. It seems to happen in large batch imports (40+ images). No filters were enabled. When I notice that they didn't import into lightroom I can go to the import directory and re-import them. It then works correctly.