Update on this, I've found this can also happen if you have any .elf in /wiiu/apps/ that isn't inside a folder. See here: https://github.com/vgmoose/hbas/issues/14It keeps saying it's downloading app directory after leaving it on for a while and when I exit (pushing the HOME menu button) it just hangs on a black screen with the awesome chiptune still playing.
But other than that great job, about time we need this lol. Now if only the 3ds had something like this for CIA homebrew...
I think it hangs and interrupts the download as it tries to treat the .elf as a directory, which then in turn leaves the initial loading thread in memory preventing you from exiting. If this is it, I should have a fix in the next update, until then you can make sure all elfs are inside folders (even if they have no icon/meta)