Why is iCloud Music (replacing iTunes Match) not syncing my playlists?

Since moving to the new iTunes, i have not been able to update my playlists - iCloud Music will upload my stored music, but not my playlists.

I use a particular playlist very regularly, and i want that to be updated.

How can i resolve this?

My music is stored on an external hard drive, that is connected to my iMac whenever i am on iTunes.