I thought this was fixed back in 2011 & 2012, but I just noticed an issue today setting up a new plan set, that if one rotates view (model, or pviewport) using either DVIEW 'twist' or UCS/PLAN, the image is no longer displayed... Convert/Export the image to .JPG, .PNG, etc. (I have Raster Design), and image displays in any view.
Using Civil 3D 2014 SP2, Windows 8.1