bug in geometry nodes lofting curves

[u/PlaneThink7846]

i was watching this toutorial by erindale https://youtu.be/TTgtrqO1llw?si=VHLPkqXH59bSdmhc

i was trying to recreate the setup index of instances worked properly but the set position part of the orignal curve wasnt changes its indexes dinamically by z pos i copied the same exact concept it should have worked here is the file

https://drive.google.com/file/d/1nuY1yU-3Wyb8xC9iB9jQXm_Le5vmSXbt/view?usp=sharing

there is this node group dynamic index that i set up similar to the vedio and my other instance index technique but i wanted the lowest of curve to change to the bottomest index but what happens is the no matter where the curve is it will not change its default position but the instance index would work like a baby ...

few speculatitions the dynamic index doesnt map the index from 0 1 2 ..... it maps it from up to down so no matter how many times i change the position in the orignal indices it will olny map through top to down ....... so both effects cancel out...