Problems with upgrading to org-mode 9 and org repository

Question

I have Emacs 25.1 (9.0) on macOS Sierra from Homebrew and M-x org-version shows version 8.2.10. On org-mode official website, I've seen that the latest version is 9.0. It's not that I'd use any of the newest features, but it bothers me that Emacs won't update. I have the following lines in my init.el:

(require 'package)
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/") t)
(add-to-list 'package-archives '("gnu" . "https://elpa.gnu.org/packages/") t)
(add-to-list 'package-archives '("org" . "http://orgmode.org/elpa/") t) 
(package-initialize)

Running M-x package-list-packages seems to at least connect to repositories and fetch some metadata (there is some activity on the mode-line and apparently no error is returned). Pressing U-x says it has no packages to update and the curious thing is that while I see packages from melpa and gnu, there's nothing from org repository (see screenshot). Why can't I update to org-mode 9.0 and why there's no package from org repo in my list?

On Windows 10 (Emacs 25.1.1), with the exact same init.el as on macOS, I have org-mode version 9.0.6.

Answer 1

Apparently, I didn't had org-mode installed from repos, it was the built-in one from Emacs, thus it didn't update from repos. So, I selected it from the packages list by pressing i, installed it, and I now have the latest version on macOS too.