Im sorry I didn't take a picture, but I just checked my 17 Legacy 3.6r
I have 1 more button than you, But still have one blank. In my car its the second from the right in the top row I believe that's blank.
I think the extra one I have is to turn off the parking sensors.
Id bet the missing swich in the top row is something only the Outback has and is omitted from our Legacy's.