Repeating event shows on wrong day

We have a high council meeting set as a recurring event on the 2nd and 4th Tuesday of each month. Works great 98% of the time, but on one month, Sept 2014, the event also shows on Sept 1, which is a Monday. When you open the Monday event it correctly shows it is only supposed to be on the 2nd and 4th Tuesday with no reference to being on Monday EXCEPT that the date for the event shows as Sept 1, which is a Monday. This event was scheduled in January as recurring for the whole year.

See attached PDF for screen shots. Any ideas why this would occur?

Strange. We've had "day before" problems, but they've been linked to Daylight Savings changes. Since you're in Nevada, I don't think that's the issue.

Also, 1 SEP, isn't just the wrong day, it's the wrong week. (1st week or 5th week of the prior month.)

I created a event just like that in my stake's calendar and couldn't reproduce the problem.

Have you tried deleting the whole series and re-creating it?

The most likely reason for this is that someone accidentally dragged one of the events to that date. You didn't show August in your screen shots, but it would be strong evidence for that option if the August 26 meeting is not showing. That would indicate that the August 26 meeting was accidentally moved to September 1, rather than September 1 somehow being an incorrectly calculated element of the series.

When that happens, the moved event is still in the series, so even though it is now an exception to the rule, showing its event details would show the repeating rule for the series.