saved student vokis do not appear for review

My students have created, recorded, and saved their vokis in a class assignment. They see a message on screen indicating that the voki has been saved (both the audio recording and the scene.) I have watched the students complete the assignment and save their work to ensure they are doing it correctly. Then, when I try to review their assignments, only a handful of vokis appear for me to review. The students are doing things identically, and some of them I see, others never appear for review. I have checked to see if the work has saved under another class, but they are just not there!