Check to see if how the Hard Drive is Formatted and the permissions set correctly
NOTE THAT ExFat Formatting is not recommended
Note that the hard drive should be a USB external hard drive not a "Flash Drive"
How to format Hard Drives using Windows and Mac Operating Systems
Audio Offline how to Batch - Re import
AVID - How to Batch Import Offline Audio
Media Databases Delete These to Fix Media Offline
Overview
Content Tools
