So you’re using custom actions for invoking actions in CRM and retrieving the results?
But you might have the issue, that you’re setting the output of your custom action using a plugin and see no result / output parameters in the response, they are simply null. In this post I want to show you, how to solve this problem.
Of course you need to set your custom action output / result inside the plugin code, like that:
pluginExecutionContext.OutputParameters["YourOutputParameterName"] = "yourResult";
In addition to that, you need to take care that your plugin exececution step is executed synchronously and registered on post stage.
Otherwise the results will not be set in the response that you retrieve. This seems to be a limitation that you need to be aware of.