Thanks for reporting this issue, Illustrator team really appreciate this.
We are able to reproduce this issue and it is currently under review.
An error occurred while saving the commentDestiney commented
It works 100% of the time for me but you MUST hit Alt first then Shift. If you hit them at the same time or use Shift first it will not select it. I use the Selection tool (not direct selection) and the use Alt to duplicate. You'll notice your cursor turns from a single arrow to a double, once it does that you can hit Shift and it will align properly.