They said the issue was something to do with stealth addresses and a missing index in the wallet. St3baS said it was something to do with a rare case of the secret key using less than 32 bytes to represent the secret key. But he has fixed the code to work for secret keys < 32 bytes. Not sure what that means, but I think it means St3baS rocks. Really glad to have him on team Shadow.
Haha thanks Pline but the credit for this fix goes to tecnovert! He is a machine!