I'm curious: was it a bad campaign, or the fact that she's a nonwhite biracial woman?
Not mutually exclusive but I have a hard time believing it's both.
It was both. She was a non-White women who ran a very poor campaign. She could only articulate herself well on the issue of abortion. Every other issue she was unable to give concise answers, avoided answering, or used synonym laced word-salads to explain her positions.
Inside word about her campaign came out that it was unorganized, she did not read her briefings, and she did not like to be shown up by anyone who seemed to be smarter than her. She also exposed her poor sportsmanship and immaturity by being unwilling to walk out on that stage at Howard and speak to all of her supporters.
Now while much of that above can be stated about Trump too, the problem is she is again a non-White woman exhibiting these negative characteristics and no amount of celebrity endorsements or mini-concerts were going to overcome them. Add in that she is in the party that presides over this economy, that is harming blue collar workers and was unable to articulate a viable solution to fixing the economy. So they also voted against her.
Oh, and in the end, abortion was not a powerful enough catalyst to encourage White women to vote for her in mass. Trump still got a huge portion of the White women vote. Something I warned you could be a possibility in this very thread.