Users who have updated to GNOME 3.22 recently has reported that they were unable to enable any of the extensions provided by gnome-shell-extensions in GNOME Tweak Tool.

This situation is now fixed with the following updates:

• gnome-shell version 3.22.0-1;
• mutter version 3.22.0-2;

A Linux Kernel update:

• linux-kernel-4.7.5 version 4.7.5, installed as a dependency to linux+kernel version 51;

Has also been issued as an attempt to fix issue #404: GNOME Shell crashes when attempting to change screen configurations on a Dell Vostro 14 with a Intel "Skylake" processor, and display artifacts found on both external and internal screens.