As you can see by the thread, several users have done what has been suggested here, but it has not fixed the issue. There is obviously something going on here beyond simple hard resetting my devices. Maybe the reminder database for the calendar has been
changed in someway or the OS's expectation of what is occurring, but there is definitely an issue that needs addressing.
As a business user of Windows 10 and Windows 10 mobile, and the thrust that MS is making to have a big impact on this market, I would suggest this be addressed as a high priority.
If it would be helpful, I certainly volunteer to provide additional information or give a log dump of some kind.
Thanks!!
Rob.