I managed by adding
unset( $form[‘fields’][‘categories’][‘attributes’][‘data-multistep’] );
to the snippet:
add_filter(
'hivepress/v1/forms/listing_submit',
function( $form ) {
if(isset($form['fields']['categories'])){
$form['fields']['categories']['multiple'] = true;
unset( $form['fields']['categories']['attributes']['data-multistep'] );
}
return $form;
},
1000
);