Network Manager (nm-applet) not starting for new users

[FerVira]

Expected Behavior:

New system users, after their account is created, will login and have access to networking if they have the sufficient privileges.

Real Behavior:
Network Manager (nm-applet) is not available in the panel for new user accounts, and manually running nm-applet does not start the network manager.

I needed to create 2 accounts for different users, and gave them administrator level and also permission to create and connect to networks.
But nm-applet does not autostart and do not launches running from the terminal. It simply won't say anything after running nm-applet. There's no simple way to make it run.

I followed the workarounds for previous releases, such:
* making sure that "indicator plugin" is active on the panel,
* and, in Application Autostart tab of "session and startup"
    * "network" is configured to autostart,
    * "Indicator Application" are configured to not autostart,
    * added nm-applet command for it to autostart.

As a system administrator I can't figure out what else should a user do to access networking.

Network Manager is running for the default (1000) user. (BTW default user is connecting to WI-FI without specific permission to do it.)
The new users accounts were given users ID below 1000 for they to not appear on login window. (My need is to recreate a previously used users scheme, used on ubuntu studio 10.10, with the same users ID in order to copy user's files directly without messing with file permissions.)

NOTE: We are running "ubuntu desktop" sessions, after installing "ubuntu studio" packages, on a fresh install of Ubuntu 16.04 LTS. New users are being created on "users and gropus" option in the System category of the Whisker menu.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xfce4-panel 4.12.0-3ubuntu2
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CurrentDesktop: XFCE
Date: Sat Jun 11 19:22:19 2016
ExecutablePath: /usr/bin/xfce4-panel
InstallationDate: Installed on 2016-06-09 (2 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
SourcePackage: xfce4-panel
UpgradeStatus: No upgrade log present (probably fresh install)

[FerVira (vira)]

UPDATE: nm-applet began to start normally after two system reboots. (User logout and re-login did not fix it.)
This issue didn't affect user accounts created with User IDs equal or major than 1000.
So, THIS BUG ONLY AFFECTS: new user accounts with User IDs below 1000, and just after system is rebooted twice.

Sorry for our sensibility, we don't use to reboot very often. :D

[Theo Linkspfeifer (lastonestanding)]

nm-applet has been updated in 16.04, so this bug needs to be verified against the new version (1.2.6-0ubuntu0.16.04.4).

[Launchpad Janitor (janitor)]

[Expired for network-manager-applet (Ubuntu) because there has been no activity for 60 days.]

[Launchpad Janitor (janitor)]

[Expired for xfce4-panel (Ubuntu) because there has been no activity for 60 days.]