I have a seedgrown nepenthes merrilliana that is about two years old or so. It has never pitchered other than when it was a very small seedling. It gets good conditions. 5-6 hours of light. Good water, consistent humidity. Other plants near it are pitchering. This one flat out refuses. If you see the photo, the tendril swells and appears like it is about to form a pitcher, but it doesn’t.
Obviously, the plant has never traveled or suffered climate shock. It has been repotted exactly once, over a year ago, as I am aware that merrilliana is not a big fan of root disturbance.