Can’t add new posts programmatically

I am trying to add new posts based on a json file programmatically, with one of the fields being a file field. This is what an object from the json might look like:

"title": "Visualisering av ?gande i startupf?retag",
    "forfattare_1": "Dana G",
    "forfattare_2": null,
    "forfattare_3": null,
    "pagaende_avslutad": "avslutad",
    "field_handledare_value": "Daniel L",
    "field_foretag_value": "Qoorp",
    "field_amnesgranskare_value": "Mats L",
    "field_estimated_value": "2017-12",
    "field_ovrigt_value": null,
    "field_presentation_value": "2017-12-18 12:15:00",
    "field_presentation4_value": null,
    "field_presentator_value": "Dana G",
    "field_presentator2_value": null,
    "field_abstract_value": null,
    "opponent_1": "Karl L",
    "opponent_2": null,
    "opponent_3": null,
    "filename": "1802_Dana_G.pdf"

And the following is my code:

$pod = pods( 'examensarbete' );
$str = file_get_contents('./cleaned_data.json', true);
$json = json_decode($str, true);

foreach ($json["0"] as $index => $exjobb) {
  $filename = pathinfo($exjobb['filename'])['filename'];
  $file_POST = get_page_by_title($filename, "OBJECT", 'attachment');

  $data = array(
    'post_status' => 'publish',
    'pagaende_avslutat' => $exjobb['pagaende_avslutat'],
    'post_title' => $exjobb['title'],
    'rapport' => array(
      'id'    => $file_POST -> ID,
      'title' => $file_POST -> post_title),
    'forfattare_1' => $exjobb['forfattare_1'],
    'forfattare_2' => $exjobb['forfattare_2'],
    'forfattare_3' => $exjobb['forfattare_3'],
    'beraknas_fardigt' => $exjobb['field_estimated_value'],
    'handledare' => $exjobb['field_handledare_value'],
    'foretag_institution' => $exjobb['field_foretag_value'],
    'amnesgranskare' => $exjobb['field_amnesgranskare_value'],
    'ovrigt' => $exjobb['field_ovrigt_value'],
    'opponent_1' => $exjobb['opponent_1'],
    'opponent_2' => $exjobb['opponent_2'],
    'opponent_3' => $exjobb['opponent_3'],
    'presentationstid_1' => $exjobb['field_presentation_value'],
    'presentationstid_2' => $exjobb['field_presentation4_value'],
    'abstract' => $exjobb['field_abstract_value'],
  );
  $new_exjobb_id = $pod->add( $data );
}

However, running this code does not create a new post of the pods-type “examensarbete”. What am I doing wrong? I don’t get any error messages, just a blank page running this script.