I am in the process of migrating my photo processing tasks in LR/PS from Windows to Mac. I have all my photos on external hard drives that I used previously with Windows. I can view these volumes and import files to Lightroom ok but cannot create subfolders, move or copy files, etc. For example, when I tried to create subfolders in LR for a folder of images that I had just imported, I got this message: The folder /Volumes/Seagate Backup Plus Drive 1/Photos_FromBlueSeagateSlim_2TB/Duke_inCourtyard_2016/In Progress could not be created on disk. This leads me to think there is some sort of file/device incompatibility issue with trying to write to the external drives. Please help!