Curious network problem: advice appreciated

I’ve just acquired an MXQ Pro TV Box running Kodi 16. It’s wire-connected to my router, as is my Windows 7 desktop PC which holds my media files in a main directory named MEDIA and various sub-directories.

The problem is that while Kodi recognises the main Media directory it only sees one of the subdirectories and its files (which play flawlessly).

With a previous media player, connected in exactly the same way, every directory was picked up and accessed with no problems. I’ve not changed any network or sharing settings on the PC.

Obviously I’ve searched around for information on this but haven’t found anything on this specific problem. So any thoughts and advice would be very welcome. Many thanks.