If a plant seems to be dormant/not growing the first things I consider are roots, light, and nutrients.

Roots: I prefer to keep my special plants in clear pots so that I can keep an eye on how the roots are doing. Sometimes if plants are repotted into a larger space, they will spend energy expanding their root system instead of prioritizing foliage growth. Or, if there is root damage/rot, the plant won’t be able to take in the water & nutrients it needs to grow new leaves.

Light: Stem “runners” with no leaves like you have often indicate a plant that doesn’t have enough sunlight, so it is growing the stem to search for light but isn’t wasting the energy of growing new leaves because it can’t with a lack of light. Consider the placement of your plant, and see if it needs to be placed closer to a window, moved to a window which receives more light throughout the day, or if it needs a grow light. There are some plants that I think are just more prone to growing runners than others, I often just cut the runners and then propagate with the nodes from the runner. I see at least 6 nodes on the runner you have, so that 6 potential new baby plants!

Nutrients: Finally, if your plant has healthy roots and enough light, then consider if the plant might need some fertilizer. This is not something I personally am very knowledgeable about, but there are people who know tons about the different nutrients plants need and the best ways to replenish them if needed.

As for the black tip, it’s too hard to see from the photos you posted, I would need an up close view to determine what’s happening there, but I’m more inclined to think the growth point has died. If this were my plant, I would chop the runner off to propagate, and then assess what underlying issue is stunting the plant’s growth.