When one looks to adjust an action date, clicking on the calendar button brings up a mini-calendar.   When one clicks on the 4th row of dates and if one mistakenly double-clicks, it is easy to mistakenly mark the "Action Completed" as completed or not completed through the 2nd mouse click.  Options to fix this could be to move the positioning of the calendar or "action completed on" line.  Or you could remove the clickable part of "action completed on" to avoid this.