I'm making my head texture like i always do.

its 128x128
the image takes up the entire canvas.
when i convert it to spinning globe there is a huge transparent chunk in the back. how do i get rid of it?

I've heard that the game "auto fixes" it.I mean the chunk does not appear ingame.
Did you tried the texture ingame?

this is just a Bug with gimp , happens every so often with me also , try making a new spinning head that should probably fix it after 1 or more tries