hook_insert and hook_update not working with custom content type

At one point in development these functions were working, but today the form populates if there's data, but changes don't make it to the database. Similarly new data aren't inserted. hook_insert doesn't even seem to be called, as a message from drupal_set_message in the function doesn't display. All suggestions welcome. These are long functions so I haven't included everything.

function cpo_form($form_state) {
  global $user;

  if(is_object($form_state) && isset($form_state->nid)) {
    $nid = $form_state->nid;
  } else {
    $query = "select nid from {cpo} where cpo_id = '$user->name'";
    $nid = db_result(db_query($query));
  }

  $node = node_load($nid);
.
.
.

  // handle standard fields (conditionally)
  $type = node_get_types('type', $node);
  if ($type->has_title) {
    $form['title'] = array(
                           '#type' => 'textfield',
                           '#title' => check_plain($type->title_label),
                           '#required' => TRUE,
                           '#default_value' => $node->title,
                           '#description' => t("First name, middle initial, last name"),
                           '#required' => TRUE,
                           '#weight' => -10,
                           );
  }
  if ($type->has_body) {
    $form['body_field'] = node_body_field(
           $node,
                                          $type->body_label,
                                          $type->min_word_count
                                          );
  }

  // custom content fields

  $form['cpo_id'] = array(
                          '#type' => 'value',
                          '#value' => $user->name,
                          );

  $form['cpo_title'] = array(
                             '#type' => 'textfield',
                             '#title' => t('Title'),
                             '#default_value' => isset($node->cpo_title) ? $node->cpo_title : '',
                             );

  $form['cpo_first_name'] = array(
                                  '#type' => 'textfield',
                                  '#title' => t('First name'),
                                  '#default_value' => isset($node->cpo_first_name) ? $node->cpo_first_name : '',
                                  );

  $form['cpo_middle_initial'] = array(
                                      '#type' => 'textfield',
                                      '#title' => t('Middle initial'),
                                      '#default_value' => isset($node->cpo_middle_initial) ? $node->cpo_middle_initial : '',
                                      );

  $form['cpo_last_name'] = array(
                                 '#type' => 'textfield',
                                 '#title' => t('Last name'),
                                 '#default_value' => isset($node->cpo_last_name) ? $node->cpo_last_name : '',
                                 );
.
.
.                             
 $form['submit'] = array('#type' => 'submit', '#value' => t('Save'));

  return $form;
}

function cpo_insert($node) {
  drupal_set_message('in insert');
  if (!isset($node->cpo_association_memberships_other)) {
    $node->cpo_association_memberships_other = '';
  }

  if (!isset($node->cpo_company_bio)) {
    $node->cpo_company_bio = '';
  }

  db_query(
           'INSERT INTO {cpo} (vid, nid, cpo_id, cpo_title, cpo_first_name, cpo_middle_initial, cpo_last_name, cpo_degrees, cpo_company_name, cpo_company_website, cpo_association_memberships_other, cpo_email, cpo_phone_day, cpo_phone_cell, cpo_fax, cpo_annual_maintenance_fee, cpo_paid_through, cpo_certified_since, cpo_address1, cpo_address2, cpo_city, cpo_state, cpo_zip, cpo_country, cpo_company_bio, cpo_approved_directory_display, cpo_is_for_admin_use_only)'
           . "VALUES (%d, %d, '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', %f, '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', %d, %d)",
           $node->vid,
           $node->nid,
           $node->cpo_id,
           $node->cpo_title,
           $node->cpo_first_name,
           $node->cpo_middle_initial,
           $node->cpo_last_name,
           $node->cpo_degrees,
           $node->cpo_company_name,
           $node->cpo_company_website,
           $node->cpo_association_memberships_other,
           $node->cpo_email,
           $node->cpo_phone_day,
           $node->cpo_phone_cell,
           $node->cpo_fax,
           $node->cpo_annual_maintenance_fee,
           $node->cpo_paid_through,
           $node->cpo_certified_since,
           $node->cpo_address1,
           $node->cpo_address2,
           $node->cpo_city,
           $node->cpo_state,
           $node->cpo_zip,
           $node->cpo_country,
           $node->cpo_company_bio,
           $node->cpo_approved_directory_display,
           $node->cpo_is_for_admin_use_only
        );
}