Howdy,

This was originally going to be a support question, but I ended up finding a way to make it work for me. if anything, I’d love feedback on whether or not you had a better method. Otherwise, I’m dropping my code snippet here for other users to find.

Woocommerce has a custom theme support for theme developers that allows for specifying the number of rows and columns on a catalog page. https://docs.woocommerce.com/document/woocommerce-theme-developer-handbook/#section-7

In Search & Filter Pro, there is a setting to specify the results per page, which will completely override this customizer setting.

Here is the code snippet I used to get around this:

function prefix_filters_post_count( $query_args, $sfid ) {
    // If search form ID = 150, the do something with this query. edit to your form ID.
	if ( 150 === $sfid ) {
        if ( function_exists( 'wc_get_theme_support' ) ) {
            $product_grid = wc_get_theme_support( 'product_grid' );

            $rows = isset( $product_grid['default_rows'] ) ? get_option( 'woocommerce_catalog_rows', absint( $product_grid['default_rows'] ) ) : 5; // 5 rows as a fallback
            $columns = isset( $product_grid['default_columns'] ) ? get_option( 'woocommerce_catalog_columns', absint( $product_grid['default_columns'] ) ) : 3; // 3 cols as a fallback

            $count = max( 1, $rows * $columns ); // return rows*columns, or fallback to 1 in case of error

            $query_args['posts_per_page'] = $count;
        }
	}

	return $query_args;
}
add_filter( 'sf_edit_query_args', 'prefix_filters_post_count', 20, 2 );