In your second point wrangle node you're attempting to use a detail attribute named 'minHeight' which doesn't exist as a detail.
So with no actual detail attribute it reads back 0. So subtracting 0 doesn't change anything.
The previous point wrangle node you have it set to run over points so the attribute 'minHeight' gets created as a point attribute, not a detail attribute.
So you'll want to change the nodes run over parameter to detail in order that in the next wrangle node you have that detail attribute available.
BabaJ In your second point wrangle node you're attempting to use a detail attribute named 'minHeight' which doesn't exist as a detail.
So with no actual detail attribute it reads back 0. So subtracting 0 doesn't change anything.
The previous point wrangle node you have it set to run over points so the attribute 'minHeight' gets created as a point attribute, not a detail attribute.
So you'll want to change the nodes run over parameter to detail in order that in the next wrangle node you have that detail attribute available.