In my iTunes library there are many tracks that have the cloud with embedded arrow (indicating that I need to download them from the cloud), but which are grayed-out, so that I can't download them, play them, or do anything. Can you tell me what is wrong?
Check that "iCloud Status" is being included in your current View->View Options, and see what it says for your greyed-out tracks. For me this shows all my grey songs as "Waiting", even though my iCloud Download icon shows the download arrow -- indicating that these songs never uploaded to the iCloud like they should have (for whatever reason), but that iCloud knew they were supposed to.
And troubleshoot from there...