Changing the mirror with dropdown list "Download mirror" don't work

[luckyrings]

package: software-properties-gtk

It doesn't allow me to change the download mirror form the dropdown list. I can select "main mirror" or "other", but it jumps always back to "Ukraine".

Actually the promplem now happend previously I was able to change it. Now I wanted to change from "Ukriane" to "Chartie, Germany, Berlin" but even when I select this from list, it shows always "Ukraine" and does not change.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: software-properties-gtk 0.96.20.5
ProcVersionSignature: Ubuntu 4.4.0-64.85-generic 4.4.44
Uname: Linux 4.4.0-64-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.5
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Mar 10 10:49:04 2017
EcryptfsInUse: Yes
InstallationDate: Installed on 2016-10-28 (132 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
SourcePackage: software-properties
UpgradeStatus: No upgrade log present (probably fresh install)