Problem to hide users at login screen (sddm)

[Markus Brunnbauer]

I wanted to hide users at the login screen by adding one line (HideUser...) to the file /etc/sddm.conf:
[Users]
MaximumUid=65000
MinimumUid=1000
HideUsers=<username1>,<username2>

The problem is, that only the first user will be hidden, all following users are still visible.
When I change the sequence of the users, still only the first user will be hidden.
I tried also to use the user IDs, or to use semicolons instead of comma, but nothing helps.

I asked my question to a german ubuntu forum, they think it is a bug.

Additional informations:
sudo lsb_release -rd
Description: Ubuntu 16.04.3 LTS
Release: 16.04

sudo apt-cache policy sddm
sddm:
  Installiert: 0.13.0-1ubuntu5
  Installationskandidat: 0.13.0-1ubuntu5
  Versionstabelle:
 *** 0.13.0-1ubuntu5 500
        500 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
        100 /var/lib/dpkg/status