HyperKey is defined as instructed, but I cannot use it to define shortcuts.

Using Sonoma on an M3 Macbook Pro. I have BTT installed and am trying to define a shortcut for Toggle Display Mirroring, using the Hyperkey+D. Previously, on another Mac, I had defined several shortcuts that use the Hyperkey using KeyCue. They worked great. Now, they are greyed out in the menu and don't work. I have defined Caps Lock in BTT, following the instructions in the manual, and it looks OK, but something must be wrong in how I defined it. One more thing: In System Settings, Caps Lock is defined as Caps Lock for both of my keyboards, Logitech MX Keys and the Apple Internal Keyboard.

When I try to define a shortcut in BTT, when I attempt to record the shortcut key combo, no matter how I try (pressing both at once or in quick sequence) I get a beep. In the Field it shows either "Caps Lock Key" or "D", never the expected "^-⌥-⇧-⌘-D". I can't figure what I am doing wrong. I've only done this once before on the old system, and I don't have access to that now.

in BTT you actually need to press the modifier keys while recording - the hyper key will only work outside of the recording field.

Okay; that appears to let me define a shortcut as ^-⌥-⇧-⌘-D. But When I try to use Caps Lock-D to trigger it, nothing happens. Likewise, in another app where I previously defined hyperkey shortcuts that should show in the menu (Mimestream for email), they. are all greyed out. That used to happen on my old system if, for some reason, BTT wasn't running. Starting it up activated the menu shortcut keys in Mimestream. Now they are deactivated whether BTT is live or not.
Any ideas?

Here's how my BTT screen looks now:

Does that show up as an image for you?

it could be some sort of permission problem. Is BTT activated in Settings -> Privacy & Security-> Accessibility?

Also, does BTT appear in Settings -> Privacy & Security->Input Monitoring? (here it should not appear, delete if necessary)

In your screenshot the mimestream shortcut is disabled, is that intentional?

The cupprit was the setting for Input Monitoring. THANKS! That seems to have solved my problems. Just tested three of the shortcuts including the one to Toggle Mirroring, and they all worked.