I tried using !lockout just now in a server where Fletcher has permissions management over most but not all channels. It seems that the lockout failed on all channels below the first one that Fletcher doesn't have permissions management over. (I then moved that category lower in the server and tried again, and it then worked on all the channels until the next highest channel that Fletcher doesn't have permissions management over, etc.) On my third try - which mostly worked - Fletcher did send me a message about a particular channel that Fletcher doesn't have permissions management over, but otherwise this was a silent failure.