iTunes Incorrectly stating iPhone Storage as Over Capacity

I have a very odd issue with trying to sync my music to my iPhone 14 Pro 256GB via iTunes.

When trying to add any new music files to my library to sync to my device, I've noticed that the backup fails because iTunes is reporting that I have 301GB of Documents and Data to sync! This is absolutely not the case as my iPhone reports having 140GB free of the 256GB capacity.

I only sync approx. 30GB of music from iTunes to my iPhone, and not much else.

So I'm at a loss as to why iTunes thinks that it needs to sync 300GB of data. it almost feels like it's trying to sync files from my iCloud Drive, which it should not.

Any ideas welcome.

Regards,