This sounds like a question better asked on the UA board.
Just to make this clear, you were not given boarding group #1 before as an SE, but rather as Star Alliance Gold.
Last year, I always received boarding group #1 when flying on UA with my AC ff number, but I haven't flown on UA recently.
I'm not sure myself whether things have recently changed.
Last edited by agjil; Aug 2, 2015 at 2:46 pm