Netgear R9000 - Plex server working but won't add new media

Hi,

I’ve installed my plex server fine on my R9000. All of my libraries are set up and working okay.
However, when I add new media to the folders, the R9000 isn’t seeing them. I have been into the plex app and forced a rescan but they still don’t show up. I have added the same files to my other plex server and they appear straight away.
What am I missing?

Cheers