5949jjs Children at that age do that kind of thing, as your daughter says it is a phase her daughter is going through. Ignore it.
For several years at that age my DGS actively ignored me and idolised his grandfather. We would come to the front door, he would do a body swerve round me to get to his grandfataher and more or less avoid me. I got the cold shoulder for a year or more.
I am, perhaps, more emotionally robust than you. I completely ignored it and was completely unphased by it. I just treated him the way i treated his sister, who never went through this stage, I didn't try to force attention on him and I ignored his avoidance.
Then one day we all went for a family walk through a local wood. Both children started building little dens then DGS decided to build a tiny village made of sticks. The others wandered off but I just stood by him and he began to tell me what he was building and what kind of sticks etc he needed, so I just collected what was needed, I asked about the construction and made a few suggestions. After half an hour, we decided to join the others and he held my hand as we walked along chattering about what we had done. Phase over
The main thing to remember is that it is nothing to do with you. It is a phase some children go to, a little step of independence that she doesn't have to like everyone she is expected to like. Perhaps she likes you a lot, but resents yu going home. There is no understanding exactly what is going on in a childs mind at that age.
Your daughter has got it right, ignore it, it is a phase she is going through. She is trying to wind you up. If you respond that is great and she will try to wind you up further. Ignore it and it will wind down. if no one responds when you try to wind them up, its a bit pointless.