Back when ADV Films had the rights to Robotech and the underlying Japanese source material, they actually sought to license Macross Zero. ADV went to Harmony Gold to try to get things all legally square, but suddenly Big West took the license off the market. I heard something to this effect from Tommy Yune back in the summer of 2006; here’s a panel report from SDCC in ‘07 that documents Yune telling this story to the crowd. The Macross Zero wikipedia article also cites an episode of Chris Meadows’s podcast Space Station Liberty from earlier that year where Yune talked about a potential Macross Zero deal with ADV.
Here’s why I kind of buy this story. TokyoPop solicited a release of Haruhiko Mikimoto’s Macross 7 Trash manga (here’s the press release, and here’s the page for it, complete with ISBN, on Amazon) back in 2004. It never saw print. Four years later, Toynami attempted to license the original 1/55 Valkyrie mold from Bandai to issue them with new, more TV-accurate head sculpts in the U.S. They were preorderable on Robotech.com that very summer. Here is the press release, complete with (now dead) preorder links. A year later it was reported on CollectionDX that the product was “on hiatus due to a licensing issue with Big West.” Both products were officially licensed in the U.S. by Harmony Gold. Neither came to market.
Point being, it seems clear that every time some poor fool with a head full of dreams goes to Japan to license Macross stuff they come back with little more than an emptier wallet and a broken heart. Harmony Gold, being a party to these failed projects, knows better than to even try.