iPod Classic 5th Gen Sync Issues

Hi all, I have an irritating problem and I'm not sure why it happens or how it can be fixed.

I still use my iPod classic (video) 5th Generation frequently, and I have issues with syncing it to Music.

The actual syncing part works fine, but every now and then I will have to select 'Sync music with Library' again, which means it will wipe everything on the iPod and sync It all again, instead of adding the new music like intended.

This is annoying and time consuming, as there is 1.5k songs to sync every time it does this, and with the iPod's hard drive, this takes quite a while. The computer I sync to with the iPod is the same every time, but insists on clearing the Library on the iPod because I'm syncing with a new library (or computer). I'm not! I am using the same MacBook Air as all the previous times, but sometimes it will just want me to re-sync everything and it is a massive pain.

For reference, this does not happen with my iPhone or iPad. It syncs new content like you'd expect without having to re-sync everything all over again. This constant re-sync issue only happens with my iPod. The macOS version also doesn't make a difference. I'm on macOS 15.0 Sequoia, but this has happened with the previous versions I've been on, which is Sonoma and Monterey.

To sum up, every now and then my iPod will insist on re-syncing my whole library as it's apparently different to the computer/library it last synced to, when it is the same computer and the same library but with new songs added. When it pops up saying "Syncing this iPod will replace the media from another library on "Harry's MacBook", I can't help but scream as it is the same computer, same library.

Any help would be massively appreciated. Thanks in advance!