Actually one of the parantages - ventricosa is a highlander and some of the alata are highlanders as well.
That's why they don't pitcher well in the hottest summer time. That is normal and will resume pitchering in spring / fall while temperature is much lower
Another reason is that when ventricosa grows taller with larger internodal spaces, they don't tend to pitcher very well like they are still small. Such characteristic also inherited to some of their hybrids. If that is the case, you have to wait for the basals to pitcher again ~
Heliamphora nutans is one of the heli that can be grown in lowland condition. Not all Heli behaves like nutans ~
No pure highlanders can survive in hot summer time without proper cooling except some intermediate nepenthes like maxima, truncata etc. If you really like appearances of those highlanders, you had better grow hybrids made with intermediate/lowlanders and highlanders