In some cases, the dream “explains” why this disappearing of visuals occurs (for instance, people think they close eyes, someone put their hands in front of their face, etc.) So I think it’s the same thing. Does this answer to your question?
The most common case is being able to move one’s hands and rub them or grasp an object (for instance the ground). Many people who practice WILD have problems with visuals and they can move in the dark. For instance, one people said that after his “projections”, he had to crawl until he’s far enough from his bed and the visuals come back. I also remember a LD account here when a girl said that she often lose visuals and feels herself freely floating in the 3D void, what she found very pleasant. So I think proprioception is very common in this state.
Now I think there are two kinds of black void. The one you get when relaxing deeply before a WILD and suddenly you see the dark in front of your eyes as if it was in 3D. And the dark void between two dreams, when you lose visuals. I’m talking here about the second one. The first one is closer to hypnagogics IMO, in the second one, you’re between two visual dreams but you’re still dreaming. LaBerge and De Gracia were also talking about the second one in their article.
Generally, in my dreams, it’s black. I’ve experienced once a white void. I happened curiously. Suddenly, I felt as if I was sitting into a white box (now I saw nothing but white). I recognize this as a loss of visuals, thus I rubbed my hands so that I didn’t lose consciousness. After a while, it came into my mind that I just had to open the box and there was a landscape again.
I think it’s generally an instable state. Images tends to appear after a while. Did you try to move though you don’t see anything, in order to maintain your dream awareness and not wake up? Now in some cases, it’s also possible that you were just waking up and it was a normal fading. Then there are some solutions, the most classical being “dream chaining”. Another solution, less common, is moving your eyes randomly when it occurs: it was an Alan Worsley’s technique.
Rather curiously, Ghibellini experienced quite systematically vibrations in the 3D void. As for her, those vibrations were energy (ki). So that she was practising ki or meditation exercises in this state. She thought that this energy was either outside the dreamer (then the dream was visual) either inside the dreamer (then the dreamer was feeling streams of energy and could act on them). That’s the reason why she thought that the 3D void was more important than the visual dream state.