Apple is introducing iCloud Drive. iCloud Drive is only compatible with iOS devices running iOS 8 and Macs running OS X Yosemite,
which is not yet available. Enabling iCloud Drive will prevent Todo on
your iOS device from syncing with Todo Mac (until Yosemite is released)
and other iOS device not running iOS 8. For this reason we recommend not
updating to iCloud Drive if you are using iCloud as your sync service
for Todo until Yosemite is released.
If you have already updated to iCloud Drive and have devices that are no longer syncing you will need to switch your sync service to either Todo Cloud or Dropbox.
Switching to Todo Cloud:
Switching to Dropbox:
For more information regarding the iCloud Drive update: