Thank you for the link, but the button I'm referring to does not look like the one illustrated in your link.
Unless the icon for that button has changed, along with it's name?
When I hold my cursor over the button in question, a little box pops up that says, "Stereo Interleave".
It looks kind of like this:
(((.)))
with the little dot located as centered, not down at the bottom like that.