I'll add this. You are in good position at the start of the draw, then as you draw, you are using the top of your back and neck muscles to draw. Then as you get to full draw, you let that string hand move VERY slightly forward to reach you facial references. All that contributes to the elbow raising up.
So, you are getting a slight lift of the string arm during the draw. Think draw in a downward movement to a point just BELOW your anchor, then a little lift to anchor at full draw. It's a very small distinction but trying to use a higher to lower draw will place tension lower in your back and will leave the elbow lower.
See if that helps.
Arne