There is an intermittent issue with the Sign In form : sometimes you can be redirected to the landing page, while still logged out. Checking the "Remember me" option before clicking Sign In solves this.

The fact that the redirect happens without showing an error message ("Incorrect username and/or password") means the authentication works, but the session somehow is lost after the redirect to the homepage.

I spent two hours already trying to figure out why this happens but I have no idea. If anyone has a clue, let me know. Issue 389 on Github (backend is Symfony 1.4 / php).