@Hamed The Receiver Behaviour that had this problem, once it stopped working, no longer cared how I set the key. It simply stopped working. I had, quite literally, two keys with the same Event Key, and could turn one off and the other on, and see that only the new one worked, that the old one had bitten the bullet. Could never be reused, in any way. This is the first time I've seen this particular type of bug, where a behaviour node has seemingly lost contact with the hyperPad world. It took an enormous amount of time and testing to isolate it to this being the problem. It was about the last thing I thought could happen...