I was just trying to update my post, it looks like something change in 810, if I use Media browser I'm able to see my files, also if I use cover art I'm able to see my media, except for "Media Files Sync" where in the past (710) I was able to see all my files after synchronization!!
I did click on "show files are missing from disk" in audio folder nothing showed up even after I did resynchronizing my audio files, but I did see few files from pictures & videos.
Conclusion after resynchronizing all my media files I can not see any NAS shared files from the Web admin "Files & media\Media Files Sync" but I can see all my local drive media files
not sure why.