Music imported from CDs not syncing to iPad Mini

I have music from CDs in my iTunes library. They show up on my phone just fine, but when I try to sync to my iPad Mini, all music that came from physical CDs that I imported from does not show up. I've had this issue before, and I was only able to fix it by re-importing every CD - something that took forever!

Is there a fix to this? Additionally, files that I downloaded from the internet do not show up either.

It seems like only my music that was purchased from the iTunes Store shows up. I have "entire music library" selected when I click "sync."