I think you've done pretty great so far. Can't really account for people not finding time to post. As you said already, the secret messages may have gotten out of hand in this last part. If everyone was at rapid posting speed it would of been alright, but since we hit a lull I think it just scared people away.
I think Nix is slightly weaker than the others, which is sort of how I made him so I'll find a way to work with it. Worst comes to worst, I can start upping his power level.
It might not hurt to get some more nudges towards important plot things, but I don't want to suggest much since I think you're already really close to a good balance of events.
Romans 8:31 What, then, shall we say in response to this? If God is for us, who can be against us?
1 Corinthians 13:1-3 If I speak in the tongues of men or of angels, but do not have love, I am only a resounding gong or a clanging cymbal. If I have the gift of prophecy and can fathom all mysteries and all knowledge, and if I have a faith that can move mountains, but do not have love, I am nothing. If I give all I possess to the poor and give over my body to hardship that I may boast, but do not have love, I gain nothing.