Completed Reminders not syncing to iOS from OS X Running the most recent version of OS X Mountain Lion and iOS 6.0, I'm able to sync all my Reminders between all my devices.

However, though the Reminders themselves will sync across all my devices, their completion state will only cross the same platform (that is, if I complete a Reminder on OS X, all my Macs will show as complete, but not my iOS devices, and vice versa).

Is there a setting that I can check somewhere to fix this, or is it working as intended?
Quoting a solution I found in the Apple community web site:


  I was having this problem. I changed the syncing range on the phone (under Settings > Reminders) to sync All Reminders. I then logged into iCloud and opened the Reminders tab. This actually caused the reminders on the phone to match the ones in iCloud.  I then made changes on my phone while that tab was still opened and the changes started to appear in iCould (sometimes takes a few seconds - up to 20 or 30) and synched on my iPad as well. After that, all of my changes started to sync across all devices - iPhone, iPad,Mac and in iCloud, regardless of where I made the initial change.
  
  Hopefully this will work for you too.


Link here.