Cannot add social_accounts to new contact other than the first three

I’m using the PHP SDK to build a small web app which add new contacts from dynamic data. I can successfully add social accounts for the first three social networks listed in the documentation (so Facebook, Twitter and LinkedIn), but it doesn’t seem to work with the other four (Instagram, Snapchat, YouTube, Pinterest). I get “Unknown social account field type” when trying to add a contact with these social accounts.
I use the exact same code as for the first three accounts:

$instagram = new \stdClass;
$instagram->name = $socials_instagram;
$instagram->type = 'Instagram';
$data['social_accounts'][] = $instagram;

It doesn’t seem to have anything to do with the number of accounts added to $data[‘social_accounts’], I tried removing a few and the error persists. Is there something I’m missing, or could this be a problem with the API?

Thank you