Saved PDF files are unreadable

if you can provide more info on how you are creating the pdf files and how they are being transferred to the iXpand drive that will be helpful. 

also can the files be opened on a computer? after you create the pdf can it be emailed and opened normally? Can you print the pdf from email? Im interested to see if the issue occurs during the creation of the file or when it is saved to the iXpand.