Add ServerAlias to parent doesn't work

In the Server Template in the Apache Website section, that "Create alias websites by" field is set to "Add ServerAlias to parent".
But, when creating a Virtual Server alias, it does not add a new ServerAlias parameter to the parent.
The alias will be created and it is visible in the virtualmin backend but there is no ServerAlias parameter added to the parent config file.

Greetings
Frank