register_setting sanitize callback $input is null

I am struggling to get my settings page to save my options. I’ve got it showing up correctly and it hits the sanitize function

    register_setting(
        'my_options', // Option group
        'my_settings', // Option name
        array($this, 'sanitize') // Sanitize
    );

When I run the debugger on the sanitize function, $input is null:

public function sanitize($input)
{
    $new_input = array();

    $new_input = $input;
    //Sanitize the input actually

    return $new_input;
}

The form itself is called like this:

<form id="my-admin-form" method="post" action="options.php">
    <!-- Submission Notices -->
    <div class="status-box notice notice-info" style="display: none;"></div>
    <?php
    settings_fields('my_options');
    do_settings_sections('my_section');
    submit_button();
    ?>
</form>

It turned out to be nonce related: the form didn’t have a nonce. Solved this by adding wp_nonce_field to the form.