When I open an FXML file in Intellij and press the Scene Builder button, sometimes it shows as on the following picture. Sometimes it fixes itself by restarting the IDE and sometimes some FXML files ...

I've created a new gluon (multiview with FXML with maven) project in intellij (using the javafx gluon plugin). The embedded intellij JavaFX plugin is enabled. When I open one the generated fxml files, ...