I had this same problem. If I do your custom field I don't believe it is giving me event count for that specific event name. Is there a way to do that? Like Event count where Event name = "name of the event" or something?

I have this same problem. I'd like to apply a different filter to each column of "event count" to report 2 different events from the same source and all I can figure out how to do so far is apply a filter to the chart, but not to an individual column