Feeds event subscriber stopped working

For some reason my feeds event subscribers have just stopped working.

My code looks like this, the dpm for debugging never gets fired so I think the function isn't being run.

I can't work out what's changed.

namespace Drupal\partshub_feeds_modifications\EventSubscriber;

use Drupal\feeds\Event\EntityEvent;
use Drupal\feeds\Event\FeedsEvents;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

/**
 * Reacts to feeds events to modify feed properties.
 */
class FeedsSubscriber implements EventSubscriberInterface {

  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() {
    $events = [];
    $events[FeedsEvents::PROCESS_ENTITY_PRESAVE][] = 'presave';
    $events[FeedsEvents::PROCESS_ENTITY_POSTSAVE][] = 'postsave';

    return $events;
  }

  /**
   * Acts on presaving an entity.
   *
   * @param Drupal\feeds\Event\EntityEvent $event
   *   The feed event.
   */
  public function presave(EntityEvent $event) {
    dpm($event);
    // Get the feed object.
    $feed = $event->getFeed();
    // Get the entity being operated on.
    if ($feed->type->entity->id() === 'parts') {
      $entity = $event->getEntity();
      // Get the unchanged entity.
      $unchanged_entity = \Drupal::entityTypeManager()
        ->getStorage('node')
        ->loadUnchanged($entity->id());
      // Check if the entity is new.
      if (!$entity->isNew()) {
        // Only if part is not new check values.
        if ($feed->type->entity->label() === 'Parts') {
          if ($entity->get('title')->value === 'empty') {
            $entity->get('title')->value = $unchanged_entity->get('title')->value;
          }

          // Part fitment/makes field.
          if ($entity->get('field_make')->isEmpty()) {
            $makes = $unchanged_entity->get('field_make')->referencedEntities();
            foreach ($makes as $index => $term) {
              $tid = $term->id();
              if ($index == 0) {
                $entity->set('field_make', $tid);
              }
              else {
                $entity->get('field_make')->appendItem([
                  'target_id' => $tid,
                ]);
              }
            }
          }


          // Part group code.
          if ($entity->get('field_group_code')->isEmpty()) {
            $codes = $unchanged_entity->get('field_group_code')
              ->referencedEntities();
            foreach ($codes as $index => $code) {
              $code_id = $code->id();
              if ($index == 0) {
                $entity->set('field_group_code', $code_id);
              }
              else {
                $entity->get('field_group_code')->appendItem([
                  'target_id' => $code_id,
                ]);
              }
            }
          }

          // Cross references.
          if ($entity->get('field_cross_references')->isEmpty()) {
            $references = $unchanged_entity->get('field_cross_references')
              ->referencedEntities();
            foreach ($references as $index => $reference) {
              $reference_id = $reference->id();
              if ($index == 0) {
                $entity->set('field_cross_references', $reference_id);
              }
              else {
                $entity->get('field_cross_references')->appendItem([
                  'target_id' => $reference_id,
                ]);
              }
            }
          }
        }
        elseif ($feed->type->entity->label() === 'Physical attributes') {
          if ($entity->get('title')->value === 'empty') {
            $entity->get('title')->value = $unchanged_entity->get('title')->value;
          }
          // Part weight.
          if ($entity->get('field_weight')->isEmpty()) {
            $entity->get('field_weight')->value = $unchanged_entity->get('field_weight')->value;
          }
          // Part Height.
          if ($entity->get('field_height')->isEmpty()) {
            $entity->get('field_height')->value = $unchanged_entity->get('field_height')->value;
          }
          // Part Width.
          if ($entity->get('field_width')->isEmpty()) {
            $entity->get('field_width')->value = $unchanged_entity->get('field_width')->value;
          }
          // Part Depth.
          if ($entity->get('field_depth')->isEmpty()) {
            $entity->get('field_depth')->value = $unchanged_entity->get('field_depth')->value;
          }
        }
      }
    }
  }

  /**
   * Acts on presaving an entity.
   *
   * @param Drupal\feeds\Event\EntityEvent $event
   *   The feed event.
   */
  public function postsave(EntityEvent $event) {
    $feed = $event->getFeed();
    $feeds = ['oe_references', 'sub_components', 'dimensions'];
    $id = $feed->type->entity->id();
    if (in_array($id, $feeds)) {
      $entity = $event->getEntity();
      $parent_field_name = $entity->parent_field_name->value;
      $parent_id = $entity->parent_id->value;
      $vid = \Drupal::entityTypeManager()->getStorage('node')->getLatestRevisionId($parent_id);
      $part = \Drupal::entityTypeManager()->getStorage('node')->loadRevision($vid);
      $paragraph_references = $part->get($parent_field_name)->referencedEntities();
      $paragraph_references_id = [];
      if ($paragraph_references) {
        foreach ($paragraph_references as $paragraph_reference) {
          $paragraph_references_id[] = $paragraph_reference->id();
        }
      }
      if (!in_array($entity->id(), $paragraph_references_id)) {
        $fields = [
          'field_oe_references', 'field_sub_components_', 'field_dimensions'
        ];
        if (in_array($parent_field_name, $fields)) {
          if ($part) {
            $part->{$parent_field_name}[] = $entity;
            $part->save();
          }
        }
      }
    }
  }

}

I also have a service definition as follows.

services:
  # Name of this service.
  parthsub_feeds_modifications_events_subscriber:
    # Event subscriber class that will listen for the events.
    class: Drupal\partshub_feeds_modifications\EventSubscriber\FeedsSubscriber
    # Tagged as an event_subscriber to register this subscriber with the event_dispatch service.
    tags:
      - { name: event_subscriber }

No answer to this, I was getting validation errors before the presave was fired which meant this code never fired.