Monthly Repeat Is One Day Off
I have set up a recurrent monthly event where When = "10-Nov-2018" to "09-Dec-2018", Repeat = "Monthly", Repeat On = "same date" and "Repeat Every" = "3 months".
Most repeats seem to occur as expected starting on the 10th and ending the 9th, inclusively, of the next month.
But, every few are off by a day on the start or end. Why?
Here's an example. In the first image is the recurrent event, started this month.
This is the same dialog, but I checked "Edit This Instance Only" so that I am editing the Aug-Sep 2019 event. Notice how the end date shifted for this instance.
