Went to pick my dd up from school she is age 6 in year 2, no homework book in the bag, asked the teacher who exasperated said she had told dd to put the book in her bag 3 times. I can understand why the teacher was annoyed dd is like this all the time totally ignores what she is told, we tear our hair out over it at home, you ask and ask her to do things and she just won't. Every teacher/key worker she has had since 18 months old has said the same, she just does not listen. No hearing problems - we have had a hearing test and I have another one booked to double check. She is always losing things, 3 water bottles and 3 cardigans last term despite being reminded by staff to put them in her bag. At home getting dressed in the morning is a nightmare, we must tell her dozens of times to get dressed she just ignores us and laughs! Telling her off or offering star charts rewards has no effect.
Are you sure she is deliberately ignoring you, rather than not hearing you? I'm not suggesting that there is anything wrong with her hearing, especially as you've had it checked, but she might just have her hearing "switched off" while she's doing other stuff.
A friend's middle son was like this - you could stand behind him and shout at him but he just wouldn't pay any attention - you had to physically get in front of him so he could see you, or touch him, to get him to realise you were talking to him. Nothing wrong with his ears either, just his brain was busy doing whatever he was doing, and was diverted away from listening.