In Internet Accounts, I see my iCloud account alright, but under it, "Notes" is not checked, and I cannot change that (the whole UI element is disabled):
I tried re-entering iCloud password several times, but I don't see a way to make these settings editable. Also went to icloud.com but didn't see an option for this there either. Any ideas?
OS X Yosemite (10.10.5)