How to access the popup text via primary port

According to the primary port interface document, we can read the text in popup windows (e.g., raised by popup function in ur script) via the primary port.

However, after trying to communicate with the primary port on our UR5E robot (polyscope version 5.11.0), we cannot find a message package with robotMessageType = ROBOT_MESSAGE_TYPE_POPUP even if there is a popup window on the polyscope software.

Could anyone tell me under what condition the robot will send us a POPUP message? How can I read the popup text via the primary port (or any other interface)?