File sharing in iTunes can't save file as says the required file can't be found

I have an app which records video surveys (Miituu). I export the responses within the app and then use the file sharing section of iTunes to save the exported folder onto the PC so that I can access the files. However, despite the exported survey showing in iTunes in the file sharing section and displaying a MB size every time I try to 'save to...' it comes up with an error saying

'xxx' could not be copied because an error occurred. The required file could not be found'

Any ideas?