I have to assume that you do not have "Pre allocate all files" Probably the pieces that held the data for those files did not contain data for any other files, so were never requested, therefore the disc filing system has not created a reference to the file(s) that does not exist. The client marks them as complete because to all intents and purposes they are. I have to assume here that you do not have "Pre allocate all files" because if you do, all file references, whether downloaded or not, is allocated space, and therefore a filename in the disc filing system.