I guess I made a mistake. I always stored my 130GB iTunes library on my desktop. I have now noticed tracks missing and I am wondering if it because my Desktop including the library, is migrating to the Cloud. This is anew feature in Sierra to save storage space. Can I get the Cloud to ignore my iTunes library? They are hard copies, I want to keep them on my MacBook. I have Apple Music anyway. How can I quickly replace the missing tracks? Thank you.