Problem transfering music ripped from a CD in iTunes to my phone via Kies.

[AC Question]

I have iTunes and Kies on my Mac and use these to transfer music to my Galaxy A3. Recently, I noticed that while it would still transfer downloaded music, any music ripped from a CD by iTunes would transfer as usual from iTunes to Kies, but then would not transfer from Kies to my phone. I never used to have this problem. What has changed and how do I fix it?