Google Speech to Text output variable not filled


I am using the GoogleSpeech.Activities.GoogleSpeechToText to build a robot. It seems that the activity does not consistently write to the specified output variable.

The spoken text is transcribed correctly to the built-in log mechanism of the activity. On some occasions it also fills the output variable, on other occasions it needs a few seconds to process, meaning that the robot is already going to the next step without filling the output variable. The log message only appears later, when the robot has already moved on.

Has anyone else experienced this and how do I solve the issue?