{{owner_name}} field in messages not working?

We have found that putting {{owner_name}} in the subject line of an email has a different result to putting it in the body of an email.

If you put {{owner_name}} in the email body, it correctly substitutes the name of the user’s owner. However, when the tag is in the subject line, it incorrectly substitutes the “From” name setting of the email template.

The screenshot below illustrates the problem.

So my question is, is there another merge field that provides the owner name correctly in the subject line?