Mail aliases plugin not honouring namespace?

[Marc Roos]

I have

namespace {
  disabled = no
  hidden = no
  ignore_on_failure = no
  inbox = yes
  list = yes
  location =
  prefix =
  separator = /
  subscriptions = yes
  type = private
}
namespace Archive {
  disabled = no
  hidden = no
  ignore_on_failure = no
  inbox = no
  list = yes
  location = mbox:/home/mail-archive/%u/
  prefix = Archive/
  separator = /
  subscriptions = yes
  type = private
}

Without aliases, folders are created at /home/mail-archive/%u/ which is 
expected

When I am adding these mailbox aliases

mailbox_alias_old = Archive
mailbox_alias_new = Archives

These folders are created in the default namespace

.Archive
.Archives.2018
.Archives

Is this as expected? I am at least not expecting it.