After looking through the logs myself, I was able to find the problem files and it turns out... they were encrypted (*FacePalm*). How they got that way is still a mystery, but since I share this storage with other users on my home network it is not too surprising.
It would have been nice if DrivePool was able to give me some of the actual file names / paths in the error message, but after finding the logs files it wasn't too hard to find what I needed.
Thanks for the help!