Question: I have Blank screen disabled but my PC seems to be ignoring this. This issue also ignores the [Caffeine](https://extensions.gnome.org/extension/517/caffeine/) extension. This is pretty recent behavior as it's been working for a long while now.

[![Power settings](https://i.stack.imgur.com/6nLZm.png)](https://i.stack.imgur.com/6nLZm.png)

Disabling idle-dim in dconf seems to have done it.

Answer: 
This is from another [answer](https://askubuntu.com/questions/1000734/prevent-a-workstation-screen-from-dimming/1000745#1000745) I posted recently. You may not need the Login screen section.

Terminal CLI method
===================

To prevent screen from turning off you need two settings, one under battery power the other when plugged into wall outlet (A/C).

For battery timeout:
--------------------

```
gsettings set org.gnome.settings-daemon.plugins.power sleep-inactive-battery-timeout <time_in_seconds>

```

For AC timeout:
---------------

```
gsettings set org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout <time_in_seconds>

```

So for both Battery and A/C set the time to 0 (never).

For Login screen:
-----------------

```
gsettings set org.gnome.desktop.screensaver idle-activation-enabled false

```

Disable dimming screen when idle:
---------------------------------

In [Unix & Linux](https://unix.stackexchange.com/questions/257329/laptop-screen-dims-after-20-seconds-cannot-change-that/258886) someone complained when on battery screen dims every 20 seconds and wants to turn that feature off:

```
gsettings set org.gnome.settings-daemon.plugins.power idle-dim false

```
I just want to add, that as a troubleshooting step w.r.t. my ...

Conspiratorially derived answer, that Ubuntu "Did Not Want" me logged into "Gnome on Xorg" ... as it sure seemed.

After a restart and the issue gone ... again, I specifically logged out of "Ubuntu" and logged back in via "Gnome on Xorg",

and No Problems! Issue APPEARS gone still?? (all other things being equal)

... So what has changed since this morning?

You tell me!