In an Intro phase of a scenario, chat messages (added through kbTell or sideChat and its variants) are displayed in a different form in the lower left corner of the screen, instead of how the chat box is set up by default. No matter if the layout is set to default or moved by the user in the Customize Layout tab like in here:
The chat messages will be displayed like this:
Messages displayed in Intro phase, unlike those in actual Scenario phase, are not removed when user restarts the phase or goes back to editor (if Intro is previewed) and will be displayed until they fade out. On restart they will stack up on each other like the GUI was never destroyed.