General advices for setup (whose fault? KVM switch, monitor protocol, Twinkle Tray, none or... Microsoft Store?)

[UneVreche]

TLDR : if some dark magic seems to apply, please consider installing Twinkle Tray with the .exe file available on their website, not through Microsoft Store (and try other cables and ports too). It solved my problems.

Now here is my story

Context
I recently bought a KVM switch to handle different PCs (let's say PC 'A' and PC 'B') and one shared screen (let's say screen 'A'), keyboard, mouse and audio device between those PC's. I have also another screen (let's say 'evil screen'), which is an old little television with no DDC protocol, wired on PC 'A' directly (and that's important).
Then I installed Twinkle Tray with Microsoft Store, (since .exe file raises red Windows Defender warning), just to adjust brightness of screen A and...

Observation
...no display detected.

Experiences

• learn what DDC means, done
• read that some KVM switches may not handle DDC, done
• connect screen A directly into PC A, done, and screen A is detected... oh no, does it mean my KVM switch is the problem?
• just try to reconnect screen A through KVM switch, use a HDMI->DisplayPort cable instead of HDMI->HDMI between KVM switch and PC A, and disconnect evil screen, done, and screen A is detected... YES! KVM switch isn't the problem... but when I reconnect evil screen, only screen A is detected AND brightness slider is unusable
• connect only evil screen, done, and evil screen is detected (even though unusable since not handling DDC protocol)
• add screen A, done, but only evil screen is detected
• read some reddit and github discussions, done
• then, uninstall Twinkle Tray, go back to .exe, ignore red Windows Defender message, install... done.... and it finally works!!! (I mean, screen A is detected and brightness slider works, evil screen is detected and unusable since not handling DDC protocol)

[xanderfrangos]

Yeah, I advise using the .exe over MS Store version due to the MS Store version acting weird. They're literally the same executable, but Microsoft does something to mess things up for some users. The MS Store unfortunately is the majority of users, too. It's how most of them find Twinkle Tray.