Seems to be working fine on the default style and it doesn't seem like guests have access to the style where this is a problem.
This could be a case of outdated templates, or a merging of outdated templates that has gone wrong. However, because it seems to be style specific and it can't be reproduced on the default XF style (e.g. here) then it would seem to be an issue with your style rather than a bug within XF itself.