I can confirm that this indeed does not work. I thought maye the device needs to be enabled first? But calling
DownButNotOut.Enable()
Prior has no effect.
[Edit] I know this is not really a solution to the problem, but I did find a work around. You can place a trigger_device and in the details pane set the Trigger event to the down_but_not_out_device and then in verse Subscribe the TriggeredEvent like so:
DownButNotOut.TriggeredEvent.Subscribe(PlayerDowned)
With the PlayerDowned function defined as:
PlayerDowned(InPlayer : ?agent):void= Print("This should now fire!") if(Player := InPlayer?): Print("Player Downed.")