Reminders constantly un-completes completed tasks!

I have an irritating issue with my Mac Reminders. I run 4 devices - an iPhone 5, an iPad, a Macbook Pro and an iMac. From what I can gather, my Macbook Pro seems to think that it is the dominant device and constantly overrides the other devices. For example, I receive a reminder alert on my iPhone, complete the task and mark it off as completed. When I open my iPad, the task has been updated and likewise on my iMac. However, later that evening when I open my Macbook up, the reminder alert appears (which I close) and then the task is updated as still pending on all my other devices! I then have to tick it off on my other devices again. Unless I mark something off as completed on my Macbook, then it will override the other devices.

Just wondering if anyone else had experienced this and if there is a fix.