There are 2 different settings in Windows to check. One is in display settings & the other is the power saver settings. If you've checked both, be sure you have the newest updated drivers for your graphics card.
If you have Intel HD graphics control panel, it may be overriding your Windows settings. https://www.tenforums.com/tutorials/70157-enable-disable-adaptive-brightness-windows-10-a.html#option4
There are some posts out there saying that Windows version 1809 seems to have issues with keeping the adaptive display settings off. If you have the latest driver for your graphics card, you can try rolling back to an earlier version.
I know if I have SimCity running, but not actively using keyboard or mouse, the OS doesn't interpret the simulation as "running". I think this is what is causing your display issues, not the game itself. If none of these options help, you may have better luck searching for solutions in Windows or the manufacturer of your tv for answers. I hope you can find the issue and get back to Happy Building!