If I log out of all the WMF sites (or just delete all my cookies), and then log into http://en.m.wikipedia.org, I am automatically logged into the other desktop and mobile Wikipedias, but not the other projects (Commons, Wiktionary, etc.).
Steps to reproduce:
- Open a totally fresh browser (or delete cookies)
- Go to https://en.m.wikipedia.org/wiki/Main_Page
- Log in
- Go to https://commons.m.wikimedia.org/wiki/Main_Page
Expected result: You are also logged in on Commons
Actual result: You are not logged in on Commons
This only happens on the Main Pages as appears to be caused by CentralAuth's 1x1 images not loading on those pages.
Expected result: You should be logged in.
Actual result: You are not logged in.