Word selection using Ctrl+Shift+Arrows doesn't work in ubuntu 16.04

Ctrl+Arrows works correctly to jump between words, however when I use Ctrl+Shift+Arrows to select by words, nothing happens.

Anybody knows how to make it work? (I'm using Ubuntu 16.04)

Output of cat /etc/default/keyboard:

# KEYBOARD CONFIGURATION FILE

# Consult the keyboard(5) manual page.

XKBMODEL="pc105"
XKBLAYOUT="us"
XKBVARIANT=""
XKBOPTIONS=""

BACKSPACE="guess"

Output of gsettings list-recursively | grep -i ctrl:

org.gnome.settings-daemon.plugins.media-keys screenshot-clip '<Ctrl>Print'
org.gnome.settings-daemon.plugins.media-keys window-screenshot-clip '<Ctrl><Alt>Print'
org.gnome.settings-daemon.plugins.media-keys area-screenshot-clip '<Ctrl><Shift>Print'
org.gnome.settings-daemon.plugins.media-keys screencast '<Ctrl><Shift><Alt>R'
org.gnome.settings-daemon.plugins.media-keys screenshot-clip '<Ctrl>Print'
org.gnome.settings-daemon.plugins.media-keys window-screenshot-clip '<Ctrl><Alt>Print'
org.gnome.settings-daemon.plugins.media-keys area-screenshot-clip '<Ctrl><Shift>Print'
org.gnome.settings-daemon.plugins.media-keys screencast '<Ctrl><Shift><Alt>R'
org.onboard.lockdown disable-keys [['CTRL', 'LALT', 'F[0-9]+']]
org.gnome.Terminal.Legacy.Keybindings zoom-out '<Ctrl>minus'
org.gnome.Terminal.Legacy.Keybindings move-tab-left '<Ctrl><Shift>Page_Up'
org.gnome.Terminal.Legacy.Keybindings new-window '<Ctrl><Shift>n'
org.gnome.Terminal.Legacy.Keybindings copy '<Ctrl><Shift>c'
org.gnome.Terminal.Legacy.Keybindings zoom-normal '<Ctrl>0'
org.gnome.Terminal.Legacy.Keybindings zoom-in '<Ctrl>plus'
org.gnome.Terminal.Legacy.Keybindings move-tab-right '<Ctrl><Shift>Page_Down'
org.gnome.Terminal.Legacy.Keybindings close-window '<Ctrl><Shift>q'
org.gnome.Terminal.Legacy.Keybindings new-tab '<Ctrl><Shift>t'
org.gnome.Terminal.Legacy.Keybindings paste '<Ctrl><Shift>v'
org.gnome.Terminal.Legacy.Keybindings close-tab '<Ctrl><Shift>w'
org.onboard.lockdown disable-keys [['CTRL', 'LALT', 'F[0-9]+']]

dconf dump / | grep -i ctrl produces empty output

As @N0rbert suggested, I checked Guest session and found out that Ctrl+Shift+Arrows shortcut keys work correctly there, which means it's a matter of settings in my account.

I started to backup and remove "." folders in my account and at some point I did something wrong and my Unity settings were completely reset and Ctrl+Shift+Arrows started to work correctly.

To my regret I didn't correctly backup my wrong settings, so at this point I can't know where exactly these settings are saved, but I'm sure it's related to some Unity settings...

One thing that could cause this, is activating this feature:

Settings/Universal Access/Pointing & Clicking/Locate pointer

It states that you can find your mouse pointer pressing Ctrl, but instead, I could no longer consistently use Ctrl+Shift+Arrow.

Leaving that information here, should I do it again, at some point.

I ran into the same problem today on my Fedora 34 KDE Plasma.

Here is what worked out for me: System Settings > Hardware > Input Devices > Keyboard > Advanced > Switching to another Layout > uncheck Ctrl+Shift.

For people using Gnome together with Gnome Tweaks: there's a similar list with checkboxes, that can cause the same issue.