When viewing the Evolution graph for the alternate secondary dimension in any of the Event reports, the Evolution graph shows 0 for all secondary dimensions.
For example, the default secondary dimension for the Event Category report is Event Action which shows data for the evolution graph:
However, when switching to the alternate secondary dimension of Event Name it shows nothing for the evolution report:
The same behaviour can be observed for the other two Event reports for the non-default secondary dimension.
For information: this behavior is the same in version 4.3.1