Mouse Keys enabled/enables during session when setting shows disabled

After starting a session, the numpad behaves as if Mouse Keys is enabled. Going to Settings > Universal Access > Mouse Keys shows that the feature is disabled. To disable Mouse Keys, the setting must be enabled first, then disabled. Alternatively, the following commands must be used in terminal:

gsettings set org.gnome.desktop.a11y.keyboard mousekeys-enable true
gsettings set org.gnome.desktop.a11y.keyboard mousekeys-enable false

These settings will only persist for the session. It has been observed that the function seemingly enables itself during a session, with no known trigger. At the same time, the num lock or shift + num lock hotkey does not function. Whether that is a separate bug is another story, but neither key combination results in the accidental or purposeful activation or deactivation of Mouse Keys.

Problem observed in Ubuntu 18.04. gsettings-desktop-schemas version 3.28.0-1ubuntu1. Has been previously observed in 17.10 and 16.04.

Current temporary workaround is to add the two commands above into a script to run on startup. This does not solve inadvertent activations later on, however.

EDIT: Mouse Keys observed to enable itself when I type "xset led on" into terminal to enable keyboard backlight.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-control-center 1:3.28.1-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon Apr 30 06:36:09 2018
ExecutablePath: /usr/bin/gnome-control-center
InstallationDate: Installed on 2018-04-28 (1 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
SourcePackage: gnome-control-center
UpgradeStatus: No upgrade log present (probably fresh install)