This is the weirdest thing. There are a great number of users who cannot seem to make a custom instrument that works in the free download Halion Sonic SE.
Steinberg support has been working on this with me for weeks, and they cannot create an instrument either! What in the world!
This is crazy!!!
A British guy posted a YouTube video, with no details of the Library Creator, and his custom instruments work perfectly!
Here is his link: https://youtu.be/pRoAyJ6jf8o
This was hailed as one of the BIG features in Halion 6! Bummer!