Refreshing external source

I used to use a share on a windows machine (no security) to host my video files and it worked fine. I have recently changed to a Synology file server and although it works fine, when I add files Kodi does not seem to see them until I reboot the Raspberry Pi it’s hosted on. The share on the Synology server is protected by password & username, but Kodi seems to cope fine with this – it seems to be the only difference.

Is there a way I can do a ‘refresh’ on a directory or is there a setting I’m missing?