Most current laws, including laws mandating registries, are of no use here or in any other context. They only serve to make politicians appear to be protecting children, they give law enforcement an excuse to abuse a segment of the population, and they give parents a false sense of security. The gap between intentions and outcomes needs to be addressed.
If the caller says they have a warrant for your arrest, it is a scam. If they tell you there is a problem with your registry information, it is a scam. If they tell you a little money will clear things up, it is a scam.
You have already reported to the sheriff — at least once, twice, or four times a year – what your address is and that is all that is required of you. We know of no statutory requirement in Nebraska that you confirm your address – or any other information – when police come to your door.