Moonlight not receiving modifier keys from touch bar's "send keyboard shortcut" action

Describe the bug
I have some touchbar buttons configured to send certain keyboard shortcuts to the remote desktop software Moonlight. The shortcuts are the left shift + control + option buttons, combined with the keyboard keys x / s / q. These shortcuts should enter/exit fullscreen, show a debug statistics panel, and disconnect the session respectively.

This was working at some point in the past, but is now behaving oddly. I don't know if a MacOS update or a BTT update broke it (Moonlight app didn't change). Pressing the touchbar button almost always does nothing. If I mash the touchbar button, it will occasionally register in Moonlight, but it isn't consistent.

I have found out that if I enable "include currently pressed modifier keys", and hold down shift + control + option while pressing the touchbar button, it works perfectly every time. So it seems that it is an issue sending the modifier keys, and not sending the x / s / q button?

"Send at lowest possible system level" checked and unchecked does not change behavior.

I've tried many things but have yet to find out a way to get this to consistently work again.


Affected input device (e.g. MacBook Trackpad, Magic Mouse/Trackpad, Touch Bar, etc.):

Touch Bar. I tried rebinding this to a keyboard shortcut and it also does not trigger there, but the intent is to use the Touch Bar for it.


Screenshots

Device information:

  • Type of Mac: 2019 MBP (Intel)
  • macOS version: 26.5.1
  • BetterTouchTool version: 6.609

Additional information (e.g. crash logs, related issues, etc.):