If I emacs -Q and make sure the load path points to the git version of
org, it doesn't work. When I do so, I have
Org mode version 9.1.6 (release_9.1.6-341-g3a4fd3 @ /home/ucecesf/git/org-mode/lisp/)
Org is probably getting loaded before you tweak the load paths. e.g. emacs -Q
foo.org would do that. That version looks like the one that's on emacs-26/master branch of Emacs.
I had written a post to fix such issues and be able to specifically use Org (1) that ships with Emacs (2) from Elpa, or (3) from git.
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