Kirk,
I use Resilio Sync to duplicate files that are saved to my Synology NAS so that a synced copy appears on my MacBook Pro, and other devices, such as my Windows 10 device. Changes made to one sub-directory replicate to all others. So, I am talking about the actual image files. Instead of trying to access my image collection on my NAS, I can access a synced copy of the collection on my Windows 10 device. I set up a test sub-directory today using this arrangement, and Photo Mechanic Plus seems to access it normally. Resilio Sync is similar to Dropbox except that it is Peer-2-Peer rather than cloud-based.
Yours,
Mark