Junk Yard · Keyboard shortcuts
Why can't I choose a certain key combination for a Junk Yard shortcut?
Short answer: Another Storage Studio shortcut (such as the Apps grid's ⌃Space) already uses it — the app never lets two of its shortcuts share keys. Change the other one first.
Because another Storage Studio shortcut already uses it. All of the app's global shortcuts — the Junk Yard ones and the Apps grid shortcut (⌃Space by default) — are kept distinct, so a combination that's taken isn't offered again. Free it up by changing the other shortcut first.
If a shortcut you've chosen does nothing, another app on your Mac may be claiming the same keys; pick a different combination.