LG 24" 4K Ultrafine Monitor brightness control slider goes missing

I found a similar issue here but for some reason I could not reply to it, only tick of "I have the same issue" and follow the thread. So I am posting this question again with the solution that worked for me.

🤞 That this remains fixable with the same hack or "fix".

Basically the issue is that my LG Ultrafine 4K 24" monitor previously had a brightness slider and I could also control it from the keyboard with CTRL+F1/F2 (or the brightness control keys). About a month after purchasing the monitor, the slider disappeared. This seems to be a monitor firmware issue as connecting to iPad also disabled this feature (where it once had the control in iPad settings but also has disappeared).

I reported it to LG but they require a technician to look at it. I need it to keep working from home so I suffered the default 100% brightness which is terrible if you use it at night in a dimmed room.

After a month the slider controls reappeared (as well as the keyboard shortcuts) for some reason and I gladly dimmed it back for nighttime use. Then this week, it again disappeared but now it defaulted to a rather dim setting which was not usable at all.

After looking up online doing all the special MacOS restarts and cable unplug and reconnection, none of it worked. I switched thunderbolt cables and none of those worked.

It hit me to do a cold unplug of the monitor's power cable (while connected to the Macbook) and powering it back on by plugging back the cable to the back of the monitor. This seemed to do the trick, resetting whatever the firmware it seemed to have to cause the brightness control from being inaccessible.

Hopefully this power cable hack will keep working in case the brightness control goes AWOL again.

Hope this helps someone else. Cheers.