I'm pretty confident sp isn't using sobel for the conversion. Try using a standard normal node. Height in sp is signed so the range goes from -1 to 1 rather than 0 - 1 Also, fwiw I try not to mix normal and height outputs from the same material in Painter. Things are a lot simpler if you stick to height.
Hmmm, so it looks like not only Height Position and Range affects Normal output, but also any Transform on normal map. I put the Normal Sobel output through a Material Transform with 25% width and height. And for reasons I don't fully understand, it results in the need to increase Normal Sobel intensity, from 5 to 20…