Instead of your H sweeping things under the rug by saying " its a phase she will grow out of it" he needs to address her and get to the root of the problem. The longer he allows this behavior of disrespect to continue she's going to think its ok to treat you like sh!t. When she ignores you that's when he has to open his mouth and ask her what the problem is.

Its obvious that there is something going on and by your H ignoring it, its not going to go away. If he doesn't do it I'd ask her and put her on the spot. If she doesn't respond I'd let it be and continue on my merry way and let him parent her. Good luck to him with that.

Next time she walks by you and ignores you say loudly "Hello!??" and give her an evil stare. Next time she walks by you and sets something down next to you like you don't exist say loudly "What the hell! Did you just do that! Apologize to me right now!"

Yes I agree with Areyou!  Bring awareness to her disrespectful behavior if your H can't seem to do it. Let her know that you will be respected in your own home and mean it when you voice it. Remain serious, firm, and look her dead in the eyes.

I feel like you need to address this behavior before it gets worse.  When SD12 was ten, she tried this.  The boiling point came when I thought I shut her hand in the van door (I didn't) so I was asking her if she was okay.  She turned her back on me.  I grabbed her shoulder and turned her around in the middle of a parking lot and told her,  "You don't turn you back on me when I am talking to you.  That is rude and I won't tolerate it."  It was the first time I ever yelled at her.  She started crying and looked to my DH, but he backed me up.  It has never been a problem again.

You really need to get DH to see how rude and destructive this behavior is.  By him ignoring it, he is sending the message that it is okay.  How would he feel if she pulled this behavior with him, or her teachers, or any other adults?  He is doing her a disservice by allowing her to be rude like that.

When is the last visit Sd had in your home? Does she only come during the summers? Anything you can think of that might have set off such a change in your SD towards you?

It sounds as if SD and you had a good relationship and enjoyed each other's time during the summer. Speaking about this to Dad isn't getting to the problem and it doesn't sound as if he has a clue what to do about it. How is SD acting around and for her father. Is the change only towards you?

Anyway, if you want to try, I'll suggest you tell her to get in the car. Be sure you have plenty of gas before. Then just the two of you go for a long ride. You will have a captured audience. She can't slam a door, jump out, walk on by or any of these other things she's doing like hiding in her room. You go , you bring up "what is going on" and you keep driving until it all comes pouring out. Don't yell at her, don't fight with her, simply ask questions and let her talk. And make it clear, you've got all day so clamming up and ignoring you the entire ride won't work. Neither of you are going home until you know what's going on. 

The worse that can happen is she will get angrier and hide in her bedroom when you finally take her home. 

If your DH won't address it, you can try.  However, I'm betting that just maybe that won't work either.  Been there, tried that.  The only thing that worked was me going into full on disengagement mode.  I don't do anything for her (SD14).  No food, no cleaning, no driving places, nothing.  She then started ramping the behavior up on DH - see above but instead of SM being the target, DH was the target.  Then she refused to come over at all - BM encouraged that and so I'm done with her.  DH hasn't been engaged in getting her back either for the time being. 

While I do think a little of it is a phase, he should absolutely stop acting like it is acceptible. Kids only grow out of these phases when they no longer work for them. He's letting her get away with being rude so it won't get better. I will say that at her age, and with how common it is to have an "evil" stepparent she might just being acting out as her friends do. I remember being that age and how I just automatically believed my bestfriends's stepmom was evil Cinderella style because of the stories. Now that we are older we both recognize her stepmom was only parenting her and was very kind to her contrary to her own dad gaslighting her stepmom. She's living out her fantasy of having an evil stepmom and while disengaging will help save your feelings, it will play right in to this romantic notion she is playing out. I would suggest talking with your DH about it and see if it is worth fixing (if he is going to back you and help make changes) or if disengaging the better route. 

Could it be that her mother is to blame for this change in behavior? If so your husband needs to address it. Maybe it's hormonal?? Either way I agree with the other posters that your husband needs to stop sweeping it under the rug and address it or it will only get worse. What you allow will continue. Ask him if the situation were reversed would he tolerate your child being disrespectful to him in his own house? Put your foot down now. If your husband won't back you up then completely disengage from your SD.

How often is she with you?  Is this a long distance visitation situation?  How is she treating your husband?

She's at an age where friends are important to kids.  If all her friends are near her mom's house, and she was removed from her friends during the time that they're all enjoying summer vacation together, she could be resentful without it having anything to do with you.  It's probably easier to take it out on you than on her father.  Could that be it?

It might be a phase. Do you think BM is saying anything to her that would make her have such an attitude change? I'm not one to always blame BM, but it seems like a drastic change.

I think your husband should talk with her alone about it. Why wait for her to grow out of it? Maybe it's something fairly simple that just needs to be hashed out. If he won't, then maybe you should. It might not change overnight, but a parent should acknowledge the message she's obviously trying to send. If it's something that can be worked out, great. If not, her dad needs to tell her it's unacceptable behavior. She doesn't have to like you, but she has to be respectful.

By not addressing it, it's like no one cares that she's clearly distressed by something. You had a great relationship, so why not nip this in the bud? It may be that she's being just as difficult with BM and something else is at the root of it (other than the step dynamic). Either way, it seems odd to act as if it's not happening.