validation_errors() returning an empty string after upgrading to 2.1.0

[eluser]mcryan[/eluser]
I've tried this on 2 instances of CI 2.1.0, one downloaded from the website, the other pulled from the stable branch on GitHub, both return an empty string when form validation fails.

Initially I noticed this on my own forms, then used the form validation example in the user guides and the outcome is the smae: <?php echo validation_errors(); ?> does not output anything.

I have tried this on PHP 5.2 and 5.3 on different servers, but the same problem is happening.

Any advice?