In the past hull was drawn with flexible wood stick: that avoid little sharp curves! ;)
here not in wood! ;)


Esle when you ask "Show Points" you will see a red Square!
So multiple points are existing on the same x,xz place on the same curve !

So you must kill them
for example draw a little straight line for keep coordinates
kill all points then move the previous...
and kill the straight line! ;)