Bridge Thumbnails only show images for jpegs

I have no idea what has happened. However, none of my tiff or RAW files show up as picture thumbnails in Bridge. Just JPEG's do. I have reset things, refreshed things etc, to no avail. If I hover over a tiff of RAW ikon (no image included) it shows some basic meta data, but not all of it. If I hover over a jpeg it shows all meta data. If I double click on a picturless tiff or RAW file it will open properly in Photshopt CC. This is a serious problem for my workflow. Help please. Thanks