Aaaah, now I get it! Man, you were sooooo close! I would say (but that's just a pretty wild guess) that for some reason you didn't let go of (stop) the mind completely. But right here: "My conscious self, which is to say my inner voice which I identify as the subject of my experiences, was lucid the entire time it transitioned from one state of sleep or of so-called subconsciousness to the next." Who or what is that "I" that identifies an inner voice (in your mind or where?) as the subject of your experiences?

Btw. in the state I was referring to there's absolutely nothing -- no thoughts, no sensations (hence no phosphenes, no emotions, and certainly no voice), not even awareness AFAICT (but that may be just how awareness of total absence of phenomena is). Therefore I stressed the transition ... hm. Frankly, I'd like to give you some more useful tip on how to continue and overcome that hurdle (that is, more useful than the questions above), but I must admit that I'm at loss. Anyway, I'll keep my fingers crossed for you!