I have my northiana in the same conditions as my other lowlanders but in a position where it receives less light. It is doing fine, but stopped pitchering for about a month after repotting. It is back to pitchering now. Here's a pic of my chamber:
You can see the ampullaria in the bottom. Maybe it just needs more light?
My little northiana:
And the large cutting I am rooting, (it is already rooted, but I still keep it in its little rooting tank for now)