Alt attribute inserted as empty When coding my formatter, I give user an option to provide alt, title and classes attributes for an image. All render beautifully, except for the alt title, which is output as flag-type, empty "alt" attribute (meaning: no equal sign or quotes), regardless of what I try to insert there.

Could the Media module be the reason - such as overriding the alt value with some hooks? If not, any ideas on what could be causing that?
Media module is almost certainly the reason.

There are patches in both http://drupal.org/node/1307054 and http://drupal.org/node/1343022 that you may find useful.