I can repro. This happens when navigating directly to chrome://md-settings/help, I never see the button appear.

if i'm reading the code correctly, the paper-button#checkForUpdates is for some reason wrapped in the span#relaunchContainer, which is hidden whenever the checkForUpdates button would be visible and vice versa.

+dschuyler

span#relaunchContainer is supposed to always be shown, and the conditional |hidden| binding logic should only be on the paper-button#checkForUpdates. This regressed at https://codereview.chromium.org/2387053004/diff/40001/chrome/browser/resources/settings/about_page/about_page.html, where the style of the about page was tweaked (and apparently the regression is not covered by a test).

I'll see how to fix the functional regression, without undoing the style tweaks that CL 2387053004 introduced.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d47dc0a551b0fedc4cd58db1498426405dd2d044

commit d47dc0a551b0fedc4cd58db1498426405dd2d044
Author: dpapad <dpapad@chromium.org>
Date: Wed Dec 07 03:38:56 2016

MD Settings: Fix "Check for updates" button regression.

Had to move "if expr" conditional logic to JS from HTML, such that
the visibility of the three buttons can be easily checked by the parent
container (which needs to be hidden when all of its children are hidden).

This CL also fixes the issue where the update status message was
erroneously visible before the user had cliced on the "Check for
updates" button.

BUG= 669259 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2538283002
Cr-Commit-Position: refs/heads/master@{#436851}

[modify] https://crrev.com/d47dc0a551b0fedc4cd58db1498426405dd2d044/chrome/browser/resources/settings/about_page/about_page.html
[modify] https://crrev.com/d47dc0a551b0fedc4cd58db1498426405dd2d044/chrome/browser/resources/settings/about_page/about_page.js
[modify] https://crrev.com/d47dc0a551b0fedc4cd58db1498426405dd2d044/chrome/test/data/webui/settings/about_page_tests.js

Verified on ChromeOS 9086.0.0, 57.0.2951.0