Sending cURL requests from php to asp.net not working

Question

I've been trying to fix this piece of code but it seems broken. If I use http_build_query($data) and just insert it into the $url at the end, it will work but if I do it the proper way (by using the curl_setopt(), it won't work.

    $data = [
        'target' => 'CupidonSauce173',
        'isDisplayed' => true,
        'langKey' => 'keyTest',
        'varKeys' => "key1|u,key2|t",
        'event' => 'eventTest',
    ];
    $payload = http_build_query($data);

    $url = "https://localhost:7020/api/notification/add";
    $ch = curl_init($url);

    # cURL Request setup.
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);

    # Certification issues / debug only.
    curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);

    $results = curl_exec($ch);

    var_dump(curl_getinfo($ch));
    var_dump(curl_errno($ch));
    var_dump(curl_error($ch));
    var_dump($results);
    var_dump($payload);

This is the return from the var_dumps.

array(37) { ["url"]=> string(43) "https://localhost:7020/api/notification/add" ["content_type"]=> NULL ["http_code"]=> int(404) ["header_size"]=> int(88) ["request_size"]=> int(141) ["filetime"]=> int(-1) ["ssl_verify_result"]=> int(18) ["redirect_count"]=> int(0) ["total_time"]=> float(0.044471) ["namelookup_time"]=> float(0.000718) ["connect_time"]=> float(0.024922) ["pretransfer_time"]=> float(0.034063) ["size_upload"]=> float(96) ["size_download"]=> float(0) ["speed_download"]=> float(0) ["speed_upload"]=> float(2181) ["download_content_length"]=> float(0) ["upload_content_length"]=> float(96) ["starttransfer_time"]=> float(0.034069) ["redirect_time"]=> float(0) ["redirect_url"]=> string(0) "" ["primary_ip"]=> string(3) "::1" ["certinfo"]=> array(0) { } ["primary_port"]=> int(7020) ["local_ip"]=> string(3) "::1" ["local_port"]=> int(60377) ["http_version"]=> int(3) ["protocol"]=> int(2) ["ssl_verifyresult"]=> int(0) ["scheme"]=> string(5) "HTTPS" ["appconnect_time_us"]=> int(33956) ["connect_time_us"]=> int(24922) ["namelookup_time_us"]=> int(718) ["pretransfer_time_us"]=> int(34063) ["redirect_time_us"]=> int(0) ["starttransfer_time_us"]=> int(34069) ["total_time_us"]=> int(44471) } int(0) string(0) "" string(0) "" string(96) "target=CupidonSauce173&isDisplayed=1&langKey=keyTest&varKeys=key1%7Cu%2Ckey2%7Ct&event=eventTest"

The web API is an ASP.NET 6 program, here is the function "add".

        // POST: Create a new notification in the distributed cache
    [Route("api/[controller]/[action]/target={target}&isDisplayed={isDisplayed}&langKey={langKey}&varKeys={varKeys}&event={notifyEvent}")]
    public async Task Add(string target, bool isDisplayed, string langKey, string varKeys, string notifyEvent)
    {
        List<string> keyList = new();
        string[] keyStrings = varKeys.Split(',');
        foreach(string key in keyStrings)
        {
            keyList.Add(key);
        }
        Notification notification = new(isDisplayed, target, langKey, keyList, notifyEvent);

        // Set the notification in the distributed cache.
        string serialized = JsonSerializer.Serialize(notification);
        await distributedCache.SetStringAsync(notification.Id, serialized);
        Debug.WriteLine(notification.Id);
    }

I really have no idea why it doesn't work. Thanks for the help.