This widget appears to have certain limitations. It's built on the Dojo framework and integrates with the Mendix client SDK. However, this combination results in limitations concerning specific actions, namely mx.data.action and mx.data.callNanoflow. It explicitly requires a Nanoflow or Microflow with a boolean return, which unfortunately means it forfeits the benefits associated with Mendix widget's action-type event.
I recommend taking a look at the “Action Scheduler” widget:
With it, you can set multiple parameters or utilize any available execution action in Mendix.