Problem scanning library

I have an issue where KODI hangs when updating my video library, it runs for anywhere between 10 and 60 seconds and then hangs, the interface remains responsive for another couple of minutes or so and then that freezes too, however the under lying OS is still running as I can browse the filesystem via ftp and download the log files.

I have 3 RPi’s (2 RPi3 & 1 RPi2+) all running from a central MySQL database which is running on a Synology NAS which also holds the files, this setup has worked really well until recently, but I’m not sure whats changed to be causing this issue. I’ve monitored the resources/load on the SQL and NAS and they’re not even close to breaking a sweat, I have restarted the NAS and only had a single RPi connected but still on joy.

Any help/advice would be greatly appreciated.

Bodi