I continue to see this happening. This morning I added a video to my library and added it to Personal Video Database. It is an exercise video, so I created a new genre called exercise and added it to the movie information (using the mass editor drop down selector). I exported the XML file, and everything was fine (it correctly added the genre and poster file path along with all details to the xml file).
I then went back and added 2 more exercise videos using the same process. This time, I created the xml file but not everything was added to the xml file. Specifically, before exporting the xml file, I manually edited the PVD Original Title field, the Also Known as field, the Genre Field, and I added the poster image to the record. In adding the Genre, I tried it twice, once using the mass editor drop down, and then once by manually typing by editing the record. After each attempt, I exported the XML file with the same results. Everything was copied to the 2 new records except the genre and poster path.
This seems sporadic...if I can determine anything specific that I am doing that results in this behavior, I will let you know.