I just saw that when I have selected the None agent in rules my selection is replaced with Event Performing Agent. This applies to existing rules ( they have changed even though I did not save any changes to them ) and new rules alike.
Despite what I see in my browser, it seems that the rule is working correctly ( i.e. that actually the None agent is set and this is a miss-representation issue ) but I am not completely sure about that.
Thanks for pointing out the UI bug and I am glad to let you know that we've fixed this issue. Can you please check and confirm the behaviour?