For the Notification Box/Bar Popup types, the text is taken from the Notification text field. The content is shown only for the Content Box Popup type. This is expected and works as designed.
@burdianov Yes, but the Notification text field (and the other fields relating to the Box/Bar) don’t display on the form when you select that type from the drop-down.
I noticed that you are using the Classic Editor. I checked it, and yes, this issue appears in the Classic Editor, but it does not occur in the current Block editor.
We will fix this and include the fix in the next plugin update.