Use Plugin with do_shortcode

Hi,

Is it possible to use this plugin with the combination of ACF (https://www.advancedcustomfields.com/)?

I created two image fields one is the before the other is the after. Selected that I get the image id.

And then I tried this:
echo do_shortcode('[noo_beforeafter items="%5B%7B%22bimg%22%3A%'.get_field('before').'%22%2C%22aimg%22%3A%'.get_field('after').'%22%7D%5D"]');

But I get this error message: Warning: count(): Parameter must be an array or an object that implements Countable in /home/httpd/vhosts/farbenkoenig.ch/httpsdocs/wp/wp-content/plugins/noo-before-after/templates/shortcode.php on line 41

I really need it to work with ACF because my whole logic is with ACF.

Thanks for a short reply,
Chris