I hope this isn't too late to help, but I've been having a similar problem (with SCORM files) where nothing would unzip and the files weren't being read. I kept getting a "Manifest not found error". I finally tracked it down to the wrong path to the unzip program on server under the top level admin settings (Server>System Paths)
when it should have been:
Hope that helps!
I guess it was a typo that someone in our network team made???