Just playing with this – I’m not getting that error, but I am getting a really funky layout, where Elementor is trying to initiate the shortcode, but also displaying the shortcode and has it all blocked up in multiple areas.
I wonder if Elementor has an issue with shortcode using the ob_get_content() function.
I’ll keep playing around with it, but the shortcode itself isn’t anything special. In fact, it’s using the syntax shown here: https://codex.wordpress.org/Shortcode_API#Output