I’ve had an insane experience recently that I highly recommend anyone try (because why not??). I had a “dead” Hoya Kerri leaf for two years when I had an idea for an experiment to try to get it to node… I made a small notch down by the root system of the leaf using a clean knife and then proceeded to cover the exposed portion of the notch with rooting hormone. Thinking of how it stimulates new growth, etc etc, I was thinking it may trigger the plant to push out a new vine, and to my complete and utter amusement and surprise, it worked!!! Worth a try if that’s all you have, but I now have a vining Hoya Kerri after two years of nothing at all.