lilypond-mode and electric-indent-mode (Emacs)

[pls]

Hi all,

lilypond-mode (Git-repository) and electric-indent-mode don't seem to get along 
too well
in Emacs. (I'm currently using GNU Emacs 25.0.50.2 (x86_64-pc-linux-gnu,
GTK+ Version 3.10.8) but I have experienced the same issues with all
other Emacs-versions I have tried before.)

When I press RET at the end of a line the indentation of that line gets
messed up (only in lilypond-mode). I tried the following three solutions to 
turn off
electric-indent-mode in lilypond-mode in my .emacs file but none of them
seems to work:

;; 1.:
(add-hook 'lilypond-mode-hook (lambda () (electric-indent-local-mode
-1)))

;; 2.:
(add-hook 'lilypond-mode-hook (lambda () (add-hook
'electric-indent-functions (lambda (pos) 'no-indent) nil 'local)))

;; 3.:
(add-hook 'lilypond-mode-hook
          (lambda () (set (make-local-variable 'electric-indent-mode)
          nil)))


I finally turned it off globally (setq-default electric-indent-mode nil)
but that's not really my favorite solution.  Has anyone else experienced
similar problems (and solved them) or is the problem sitting right in
front of my computer?

Any help would be greatly appreciated!

TIA,
Patrick