%title placeholder not always replaced in email action applied to workflow state change

I have the following email message written into the email action:

This email serves to inform you that a new content item was just moved to the Publish state in the ICS Drupal system. This means that the Publisher has approved the content and intends for it to be live. The content item is called "%title" and the user is "%username".

The %title variable is replaced sometimes, but not always. The %username placeholder seems to be always correctly replaced.