I got a mix Heliamphora a while back. It is in LFS, in a plastic pot, that I keep in my orchid case.. so the humidity varies from 60-85. It gets broken south sun. The temps stay fairly cool, I grown cool growning orchids which grown great.
So anyway, the heli grows fine...has a bunch of growth points... they are getting larger and larger as the plant grows. But each one will fairly quickly brown/dry at the tip... and just the tip. I recently put the plastic pot into a larger TC pot and packed LFS between the two, thinking it would keep the roots cooler and add a bit more humidity around the guy.
It is too early to see if this will help, but i just wanted to run this by the experts here to see if this is a common occurance.