The time value of the note where a slur ends seems to have an unwanted effect on where the slur starts, if the slur direction is opposite to default (as usually in four-part vocal scores). In the first bar of the attached example the slur behaves correctly, ending on a half note. In bar 3 the slur beginning shifts, because the slur ends on a whole note. Can you reproduce this, or is something wrong with my system?
I am sorry if this has been discussed before. In this case, I would appreciate if you could point me to that discussion.