I don't have a definite explanation, but I'll offer up a couple of assumptions since you asked.
First, it could have something to do with taxes on royalties and the statute of limitations on creditors or collection of debt. It could be a similar situation to "stale checks", where a bank isn't legally required to honor checks which are cashed after a certain time of the issue date. In other words, it's just been too long since the sale was made, and with no royalty payment information, they are only obligated to hold on to unpaid royalties for a certain period of time. I'm not certain of this, just speculation.
Another issue might be that, without any verified payment information, there's really no way for CGT to know for sure who is truly owed those royalties for that first sale, even though it's under your account. Payment information is very useful for identity verification as well as distribution of funds.
Again, this is only speculation and may not even be relevant. Definitely contact support and find out what's going on there. Good luck!
