Thanks to Leo Famulari patch here https://lists.gnu.org/archive/html/bug-guix/2018-12/msg00345.html <https://lists.gnu.org/archive/html/bug-guix/2018-12/msg00345.html>,  it is working now!

1. I downloaded graphics.scm from Guix Cgit: http://git.savannah.gnu.org/cgit/guix.git/plain/gnu/packages/graphics.scm <http://git.savannah.gnu.org/cgit/guix.git/plain/gnu/packages/graphics.scm>
2. Applied Leo Famulari patch like this: `path graphisc.scm blender-80.patch`
3. Installed form file: `guix package -f graphics.scm -i blender`
Blender 2.80 is now working fine, rendering ok!

Thank you!