We have wanted to release MADOX in HD for many years, but have been unable to do so because suitable film assets were not available. Everyone thought they had been lost, but in reality the original print was at Tokyo Genzōsho, sitting in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying "Beware of the Leopard Tank", wondering why all the other OVAs were getting released in HD and it wasn't.
As far as we can tell, the only record of its location was mangled by a manically depressed fax machine, and only the heroic efforts of our crack team of Combat Archaeologists managed to uncover the truth.
At which point, we emailed Tokyo Genzōsho and the reply was, "Yeah, sure, we've got it. Also, we like Gojira