If you try to use Alt-F, or type 1 inside the image viewer, you have to restart the device for the Image Viewer to function again. To restart properly, go to Home, Settings, Menu, Restart the device.
Regarding Amazon is taking forever to answer your question, I understand customer service is at a bind as well because Image Viewer is not really not on the feature list. I understand K1 users are having a lot of fun with the previous Image Viewer but Amazon really never pushes the Image Viewer.
The supported images format inside image viewer is just jpg, png, or gif
BMP is not supported.