old Gallery shortcode

Hi,
we have an old website where the galleries were only created with the “Add media” button, but were not inserted as shortcode [gallery xxx, xxx] in the text field.

Instead we used a

echo do_shortcode('[gallery column="3"]');

in the php code of the site, to display the pictures.

If we wanted to edit the gallery it was enough to press again the “Add media” button and the related gallery was still there.

Since the latest WP updates, pressing the “Add Media” button doesn’t show anymore the stored gallery, but it only gives the option to create a new one.

The funny part is that the above mentioned shortcode

echo do_shortcode(‘[gallery column="3"]‘);

is still working, and show the correct pictures, even if WordPress show no gallery related to the current post.

What has been changed? Why WP believes there’s no gallery assigned?

Any help is really appreciated.

Thanks