After attaching an image the raster image name is not listed in Raster Manager, but at the top of Raster Manager it says 1 of 1 listed.
Starting with Microstation XM and continuing in Microstation V8i raster images can be attached on the background, design, or foreground planes. In raster manager it will list images attached to the background plane first, then there is a line, then images attached to the design plane, followed by another line, and finally list the images on the foreground plane. In raster manager click on "View" along the command menu running across the top of Raster Manager. Here you should see background, design, and foreground plane listed. These are toggles that if toggled off any images attached on that plane will not be listed in raster manager.
Click on background plane and see if the image name populates in raster manager. If it does not then click on design plane, continuing with foreground plane if needed. When you toggle on the plane the image was attached to the name should appear in Raster Manager. You want to see 3 lines running across raster manager where the attached image names are located. This means all planes are toggled on and this will always show images attached through raster manager no matter which plane they are located on.