Q: Syncing problem

Hi abu745,

I have an article for you that may be able to explain why this syncing behavior is happening. That article can be found below:

By default, iTunes manages the content of your iTunes library (including your music, TV shows, movies, and more) manually, which gives you control over the content you want to take with you on your iPhone, iPad, or iPod touch. This is useful if your iTunes library contains more items than can fit on your device.

If you're a member of Apple Music or have an iTunes Match subscription, you have iCloud Music Library turned on. When you have iCloud Music Library turned on, you can't manually manage music. You can still manage videos using the steps below.

Move content from iTunes on your computer to your iPhone, iPad, or iPod touch - Apple Support

https://support.apple.com/en-us/HT201593

Thanks for using the Apple Support Communities. Have a good one!