iTunes albums not syncing to my iPhone

I have iTunes version 1.5.1.24 on my Mac which is running 15.1.1 - I recently inputed 15 CD's into iTunes, via an external CD drive. 12 of the 15 CD's transferred to the iPhone 15 with no issues. But three of them didn't. When I click on the iPhone icon, in iTunes, I go to MUSIC and click the albums I want to transfer. But these three, of the 15, do not show up in the box to be transferred. The other 12 do, so why is it that these three do not and how do I fix the problem? I did remove those three CD's from iTunes and re-transfered them into iTunes. They do appear in the recently inputed of iTunes but still do not show up in the MUSIC section of the synch box. Any assistance will be appreciated.

[Re-Titled By Moderator]