I had this happen to me before but it can in a shape of a black orb. And what I sense is that this darkness was like a living entity before me.

What has worked for me is that instead of expecting something from a lucid dream instead of gaining something I try to do anything I can to offer value first. Even if it's just by observing this black void or whatever it might be, give it attention, open yourself up to understanding it and allow it to feel that you are giving value instead of just expecting something first. Hope this helps.