Music from CD wont transfer to iphone

Hi

I have had trouble when I have copied my cd's to my computer and then transferring them to my iphone 12 pro. Most of them I don't have any trouble with its just a odd few. Today I copied cd1 and cd2 to my computer but only cd1 went to my iPhone. In the library it has a circle next to it and is feint which all the ones that wont copy over are the same. I still have room on my phone for music etc. but I'm not sure why they wont copy over. Any help will be appreciated.

Thanks