Events not tracking after update

I have the same issue and i pinpointed the culprit.

// Purchase and Subscribe events
add_action( 'woocommerce_new_order', array( $this, 'inject_purchase_event' ), 10 );
add_action( 'woocommerce_process_shop_order_meta', array( $this, 'inject_purchase_event' ), 20 );
add_action( 'woocommerce_checkout_update_order_meta', array( $this, 'inject_purchase_event' ), 30 );
add_action( 'woocommerce_payment_complete', array( $this, 'inject_purchase_event' ), 40 );
add_action( 'woocommerce_order_status_processing', array( $this, 'inject_purchase_event' ), 50 );
add_action( 'woocommerce_order_status_completed', array( $this, 'inject_purchase_event' ), 60 );
add_action( 'woocommerce_thankyou', array( $this, 'inject_purchase_event' ), 70 );

The event is injected to multiple hooks however most of us want to inject it on the thank you page only. The issue is with the prevention of multiple trigger logic here:

// use a session flag to ensure this Purchase event is not tracked multiple times
$purchase_tracked_flag = '_wc_' . facebook_for_woocommerce()->get_id() . '_purchase_tracked_' . $order_id;

// Return if this Purchase event has already been tracked or order state is invalid.
if ( 'yes' === get_transient( $purchase_tracked_flag ) || $order->meta_exists( '_meta_purchase_tracked' ) || ! in_array( $order_state, $valid_purchase_order_states, true ) ) {
return;
}

// Mark the order as tracked for the session.
set_transient( $purchase_tracked_flag, 'yes', 45 * MINUTE_IN_SECONDS );

// Set a flag to ensure this Purchase event is not going to be sent across different sessions.
$order->add_meta_data( '_meta_purchase_tracked', true, true );

// Save the metadata.
$order->save();

Basically it will fail the check once metadata is saved and that will happen on the first hook so your purchase event will never see the thank you page.

I needed a temp fix and I commented out the following:

add_action( 'woocommerce_new_order', array( $this, 'inject_purchase_event' ), 10 );
			add_action( 'woocommerce_process_shop_order_meta', array( $this, 'inject_purchase_event' ), 20 );
			add_action( 'woocommerce_checkout_update_order_meta', array( $this, 'inject_purchase_event' ), 30 );
			add_action( 'woocommerce_payment_complete', array( $this, 'inject_purchase_event' ), 40 );
			add_action( 'woocommerce_order_status_processing', array( $this, 'inject_purchase_event' ), 50 );
			add_action( 'woocommerce_order_status_completed', array( $this, 'inject_purchase_event' ), 60 );

and my Purchase event works on the thank you page

I just updated and gave it a test spin, however the purchase event is not tracked on the thank you page.

in facebook-commerce-events-tracker.php a check exists:

// use a session flag to ensure this Purchase event is not tracked multiple times
$purchase_tracked_flag = '_wc_' . facebook_for_woocommerce()->get_id() . '_purchase_tracked_' . $order_id;

// Return if this Purchase event has already been tracked.
if ( 'yes' === get_transient( $purchase_tracked_flag ) || $order->meta_exists( '_meta_purchase_tracked' ) ) {
return;
}

basically when the order is created it will add the meta and prevent the code being executed…

I will try to find some time tomorrow to submit a PR that resolves this.