From my experience with my friend, I am starting to believe it is something either within an individual's Bridge program or perhaps their computer. She is able to recreate the problem using raw images where I created the .xmp file. When she created her own .xmp files for 'virgin' raw images (mine, not hers) the problem did not happen. In other words, she now has a folder (with her own .xmp files for my images) where the problem does NOT occur and another (with my .xmp files for my images) where the problem DOES occur.
This is perhaps another piece for the puzzle.