Why the commit is not shown in the issue after it is closed as fixed? Yesterday I saw that I forget to commit a change in a 8.x branch of a project, so I search for the commit message in the 7.x branch and I commit the changes and push my code to drupal.org, but today I see that the commit appears in the project page but not in the issue.

If you go to see the commit you will see the issue number and reference:

https://www.drupal.org/commitlog/commit/43654/082f754b0f3780979663afea014df3cb84d0eeec


  Issue #2846726 by ...


But in the issue page the commit not appears, this can be because the issue have the Closed (fixed) status?
It is more likely the case that the service that handles the issue updates was down for some period of time. Under normal circumstances pushing a commit to D.O. will update the issue referenced in the commit message no matter what the issue status is set to...