No infact I have been able to export in all formats. Make sure you you install the NVPack that is in the UE4.12 Extras folder even if you had in a previous build. Also make sure are telling it to rebuild each time. Finally test this with a ‘New Project’.
I have done several builds from the GitHub 4.12 preview and the latest 4.12 releases with many of you problems and these tips have always got me back on track. Sadly performing a Build and an Android Rebuild can add several hours to your app creation. 