Can't enable Game Mode

Have you tried restarting your PC?

In this case, try open start and search for Feedback or from this menu click on Give us feedback to open Feedback Hub app and report this issue.

Tried restarting dozens of times. Looks like that every time. I have sent the necessary info to Microsoft through the Feedback Hub. We'll see what happens there. 

The weird thing is that no one else seems to have this issue. I can find no evidence of anyone asking about it. Clicking on the "Learn about Game Mode" link just takes you the Microsoft Xbox support page that tells you to click the button to turn it on. I can't do that since there is no button to click. 

It's all the result of installing version 1803. It worked before that. To fix it I've tried reinstalling windows, rolling the computer back to factory, uninstalling and reinstalling the Xbox app, and running the SFC scanning tool a dozen or so times.

The only thing I haven't tried is a hammer. Upside is that all games run okay.

Curious. Did you see an appreciable performance boost when using Game Mode previously ?

I've only ever seen the note - 'This PC supports Game Mode' since it was first introduced, and was of the impression

it could be toggled on/off via the Game Bar keyboard shortcut, but I've never bothered with it because Game Mode is

really only helpful  on low end machines.

While it may help a machine that is struggling to achieve playable frame rates, with an increase of a couple of fps,

it has also been known to reduce performance in some games as well. Particularly on machines with good graphics processing power.

(Unless MS have tweaked it since inception. Doubtful, as they can't even get their act together with the version updates...

Witness the current 1809 debacle).

- My understanding is Game Mode can be a handy shortcut for heavy multi-taskers as well,  but I believe you can achieve the same

results by the traditional manual method of minimising the number of Startup Programs, and reducing background tasks by

closing open Browsers or software you don't need to have running while playing a game.

.

I suppose it's more of an annoyance issue. Turning it on through the Game Bar just takes me to the above pictured section of Settings. So it's a loop.

Mine is a higher end machine so you are correct about turning things off and setting others to load when needed. That works the same for me. I use Cortana to set reminders and Game Mode silences them while playing making the experience a little easier. I've since switched to my phone for that. 
Mostly I'm just curious as to where Game Mode went after that last big update.