Repro::
Add an EventSystem to your Scene. Add an Event Trigger to an object (say a UnityEngine.UI.Image) and make a script with a method having the call signature:
public void OnDrag(BaseEventData dat)
{
UnityEngine.Debug.Log("hello");
}
Disable EasyEventEditor, notice you can connect the Dynamic BaseEventData method like in the image below:

Connect it.
Now enable EasyEventEditor. See that now the method shows as <Missing>.

Repro::
Add an EventSystem to your Scene. Add an Event Trigger to an object (say a UnityEngine.UI.Image) and make a script with a method having the call signature:
Disable EasyEventEditor, notice you can connect the Dynamic BaseEventData method like in the image below:

Connect it.

Now enable EasyEventEditor. See that now the method shows as
<Missing>.