Export not working for me

I am trying to use the Export function to extract multiple Tracks imported from and present on an external USB drive connected on my network, with all the metadata & artwork Roon has identified for them, to my regular NAS. Once on my NAS they can be picked by my UPnP server, and presentation to my Naim network player.
I am using Roon, at present, to provide a Music library management function on PC (Win7), and to manage the metadata of my Music library.

At present, the Export function tells me ‘14 Tracks left’ but has been like this for a few hours now.