Modifier-Dependent Sliders Do Not Work

I have a brightness slider on my Touch Bar that I only want visible while holding control, but it will not adjust the brightness in this scenario. Instead, the widget slides up and down without changing anything. When I make the slider permanently visible (without pressing a modifier), it works as expected.

I recently upgraded to Catalina but the problem existed before the update.

Device information:

  • Type of Mac: 2019 MacBook Pro
  • macOS version: MacOS Catalina 10.15
  • BetterTouchTool version: 3.206 (1382)

What modifier key are you using? (I think CTRL is reserved for changing the brightness of external displays)

That was it; switching to the option key from the control key made the slider work. Thank you for the quick help.