iPod 5th Gen - Wont add or sync music after update

Hi all,

Recently I updated my iPod Touch 5th Gen to the latest firmware for that model (iOS 9.3.5) and I am no longer able to add or delete music from the device through Itunes.

Basically when I add music it comes up in the music tab greyed, ready to sync. Then Itunes run through various sync cycles without adding the music.

I have tried: Restating the device. Using a new cable. Restarting my computer. Restoring from backup. Restoring the iPod. And of course... googling this for hours and hours.

Deleting music to make more space through Itunes removes it on the computers Itunes iPod music window but when I open my iPod I can still find and play that music that was supposedly deleted. Clearly Itunes does not want to communicate with my device even though it is connecting and reading it fine.

I'm at a loss here. I have 5 years worth of music on that iPod and it seems that updating it has bricked my device.

Any help would be very much appreciated. Thanks.