Found a simple solution to the problem. Turns out that renaming from a .BRD extension to a .MCM extension allowed the up rev'ed file to load successfully. The original ver 14.x file is a .BRD. Up revving with DBDOCTOR was apparently successful, but the new .BRD file would not open in APD, Allegro PCB Designer, or Allegro Physical Viewer. After the rename (and nothing else) APD loads the file successfully. Curious.