AITA for thinking my classmate is ungrateful for not saying “Thank you” after i helped her?

I’m 19F and a graduating student. I have a classmate I never had issues with before and actually liked her vibe. Problems started during our school festival where she was the lead choreographer. I won’t go too deep into that, but the event was messy and our class didn’t place. There was already tension because cooperation in the class was low, but I let it go. The real issue started when she suddenly lost a powerbank and began messaging me repeatedly about it since I’m the class president. I had no idea it was even missing until then. I told her I’d ask around, which I did multiple times, but no one knew where it went. She then insisted that if it couldn’t be found, everyone should pay for it because according to her "we all" had used it and she had warned them it wasn’t even her powerbank. The problem was that not everyone even knew about it or that it was being used by one of us. I didn’t either since I wasn’t there when it disappeared. I asked the classmate who originally borrowed it (who’s also my friend) if he had seen it. He said no, and when I told him he might have to take responsibility, he refused, saying he borrowed it but didn’t lose it. That caused an argument between us. Since I was stuck in the middle, I asked the class if they could contribute. Some others paid but it wasn’t nearly enough. When I suggested she and my friend split the remaining cost, they both refused. I was already stressed because i was dealing with this problem while also preparing for our research defense, so I told my dad about it and he helped me find a cheaper powerbank. With his help and the small contributions from classmates, we replaced it. When I finally gave it to her yesterday, she just took it without even saying thank you, more-or-so a glance at me. I was honestly shocked. I know it’s not her obligation to thank me for helping her but I’d appreciate it if she’d thank or atleast smile at me. But no, i didn’t receive anything other than indifference. I’m not pissed at the point that she didn’t thank me, i was pissed because my dad- who wasn’t even involved and just wanted to help me, paid more than everyone who was even involved here. She, the one who lost it didn’t even pay although she agreed and it was her main responsibility to take care of it. We were just there to help- she wasn’t even putting the time and effort to find it and put it all on me, and i wasn’t even involved aswell. Even my friend who i argued with about taking responsibility, has done more effort than she did. And he wasn’t even the owner.

So AITA for thinking she’s ungrateful for that??