My keywords are not syncing between iOS devices and Mac. The iOS devices(iPhone 6 and iPad Air) are running iOS 8 and recently iCloud Drive. However I have had this problem prior to switching over to iCloud Drive on iOS 8.
A while back I had the same problem with iOS 7 and resolved it by following this support document http://support.apple.com/kb/HT5824?viewlocale=en_US&locale=en_US
But the new iCloud.com does not have such an option.