@one1ofeach, I hear you. It’s hard when you feel like you know your kid best and you know that whatever the school is using to make judgements about your kid (like placement tests) may not be completely reflective of your child’s abilities and/or the full picture.
Is your child interested in getting a math challenge outside of school since he is not getting it through his classes? My child is also a mathy kid and has really enjoyed the Art of Problem Solving classes online. They are quite challenging and are intended for mathy kids.
It’s too bad when your kid has to resort to that type of online class to get a challenge, especially when you are paying to send him to BS where you expected him to get the math challenge from the school, but at this point, maybe that is what you need to do to get your kid the level of challenge he needs and maybe it will also help him be placed into a higher level class next year.