the "copy building" hotkey is B by default. I have not changed that.
if I click on an existing, built critter drop-off and press B, nothing happens
If I click on the "copy" button next to the building menu, it works
the hotkey works for every other building, it even works for critter drop-offs that aren't built yet, just placed. but not for built ones
- place a critter drop-off and wait for it to be built
- select it
- press B
I've attached my save file just in case