iPhone Reminders, iCal, tasks, and sync failure

I'm trying to use the proximity features of the Reminders app and I've run into difficulty. I can't seem to get the iCal tasks on my Mac to maintain sync with Reminders on the iPhone unless I turn off syncing for calendars on whichever device hasn't been used to edit items so that all items are deleted and then downloaded again when I turn syncing back on. For example, if I update a task in iCal on the Mac by marking it completed, its completed status in the Reminders app on the iPhone doesn't change until I bounce calendar syncing in the iCloud app on the iPhone as described above. In other words, the only way I can maintain syncing is to remove/restore the data before I make a change at either end of the sync operation if I haven't done that since making a change at the opposite end. That's not really very effective syncing. Is there any remedy for this situation? Thanks.