Jenkins embeddable build status icon not shown

I had an issue with space in the project name, so do not forget to replace spaces with %20

example:

[![Build Status](../Long%20Project%20Name/...)](.../Long%20Project%20Name/...)

Well, the question has been asked some time ago, but for others reaching it here, having the problem, that the image is still not shown within the Readme.md on GitHub/GitHub-Enterprise after performing the above mentioned configuration:

Make sure that both services are using the same protocol. In my case, we had GitHub-Enterprise running under HTTPS and Jenkins was running on HTTP.
The badge will not be shown in this case because of the possible security breach introduced by mixed content. You will find an appropriate error message in the console output of your browser (i.e. F12 in Chrome):

Mixed Content: The page at 'https://.../README.md' was loaded over HTTPS, 
but requested an insecure image 'http://.../job/master/badge/icon'. 
This request has been blocked; the content must be served over HTTPS.

It's of course quite obvious but something that can also be easily missed when searching on the wrong track.

By default DEV@cloud Jenkins instances are not visible, at all, to anonymous users. If you have configured role-based security and want anonymous users to have the selected roles, configure your system and check the box Enable read-only access for anonymous users.