Multi-Step

Hi,
I installed the Pro version of PPOM and I entered the shortcode for the Meta-Step function.
The shortcode is “add_filter (‘ppom_collapse_fields’, function ($ apply) {return true;}, 999);”

The theme is Ascend by KadenceThemes.

This action, however, blocks the operation of the site also on the administrator side. Evidently the modification to the functions.php file is incompatible.
How can I solve? Thanks