I'm not surprised at all.
Our top ranked middle school commonly placed children who qualified for higher level math or LA into lower level courses. So, your kid might be fine to take Algebra in 8th grade but they'll score better if you put them in transitional Algebra. If the kid tested for transitional Algebra they'd bump them down to the next lower level. If the parents weren't paying attention and actively advocating for their student they could end up in lower level courses all through middle school. But hey, our scores were tops in the state!!