Upgrade to iCloud Drive: "...devices below will not be able to access..."

I'm running Yosemite on a mid-2012 MBP. When I try to upgrade to iCloud Drive on my iPad or my MBP it states that my MBP will not be able to access files on iCloud Drive until I upgrade it to Yosemite. I'm already running Yosemite. Is this a bug?