I don't have a complete understanding of the Pioneer compound signal structures (some other experts in the JP1 group may know more) and I have only guesses at what the 900D format of Pronto Hex is supposed to mean (beyond the fact that it is some kind of Pioneer compound signal). Eigeny Oulianov is probably the expert on that.

I'm not too surprised that 900D got converted into a compound Pioneer signal in 0000 format with the right device and command numbers. But it isn't the compound structure I thought it would be. That MIGHT be the reason it didn't work. But I still don't know why the one learned from the original remote didn't work.