undefined method ATCF_Campaign::backers_per_price() in checkout page

Did you first install https://www.ads-software.com/plugins/easy-digital-downloads/ ?

I have the same issue after install update…
Looking the code i see that in inlcudes/class-campaign.php the function backers_per_price() no longer exists…
so i check on old versions and copy the function in line 200 aprox…
after

public function updates() {
		return $this->__get( 'campaign_updates' );
	}

/**
	 * Campaign Backers Per Price
	 *
	 * Get all of the backers, then figure out what they purchased. Increment
	 * a counter for each price point, so they can be displayed elsewhere.
	 * Not 100% because keys can change in EDD, but it's the best way I think.
	 *
	 * @since Astoundify Crowdfunding 0.1-alpha
	 *
	 * @return array $totals The number of backers for each price point
	 */
	public function backers_per_price() {
		$backers = $this->backers();
		$prices  = edd_get_variable_prices( $this->ID );
		$totals  = array();

		if ( ! is_array( $backers ) )
			$backers = array();

		foreach ( $prices as $price ) {
			$totals[$price[ 'amount' ]] = 0;
		}

		foreach ( $backers as $log ) {
			$payment_id = get_post_meta( $log->ID, '_edd_log_payment_id', true );

			$payment    = get_post( $payment_id );

			if ( empty( $payment ) )
				continue;

			$cart_items = edd_get_payment_meta_cart_details( $payment_id );

			foreach ( $cart_items as $item ) {
				if ( isset ( $item[ 'item_number' ][ 'options' ][ 'atcf_extra_price' ] ) ) {
					$price_id = $item[ 'price' ] - $item[ 'item_number' ][ 'options' ][ 'atcf_extra_price' ];
				} else
					$price_id = $item[ 'price' ];

				$totals[$price_id] = isset ( $totals[$price_id] ) ? $totals[$price_id] + 1 : 1;
			}
		}

		return $totals;
	}

hope it helps! i have long days trying to find the fix!

bye

Martin