Text widget shortcode doesn’t change
– The slider’s shortcode is in a text widget, but it doesn’t change in the frontend, only the shortcode text can be seen.
WordPress doesn’t support shortcodes in the text widgets, they only appear, if your theme was coded to show them. You could try to give this option to your theme by putting this code to your theme’s function.php file:
But we have our own widget, and you could use that instead.