Interoperability of PHP, OpenSSL and C# regarding AES encryption

Given a PHP script that encrypts a string with openssl_encrypt, I want to decrypt the output with openssl CLI and C#.
Although I can encrypt and decrypt the string in each programming language on its own with key and IV, I cannot decrypt the PHP output with openssl CLI and C#.

This is the PHP script:

<?php

function bad_crypt($string, $action = 'e') {
    if (empty($string)) {
        return "";
    }

    $encrypt_method = "AES-256-CBC";
    $key = "3d13b07f244861f2d323d1734d773ce4bd079e2c17deb5695911e1387e0b579a";
    $iv = "d9ec53dadaf1e968"; // bad practice, but this is just a test

    echo "key:";
    echo "<br>";
    echo $key;
    echo "<br>";

    echo "iv:";
    echo "<br>";
    echo $iv;
    echo "<br>";

    if ($action == 'e') {
        $output = base64_encode(openssl_encrypt($string, $encrypt_method, $key, 0, $iv));
    } else if ($action == 'd') {
        $output = openssl_decrypt(base64_decode($string), $encrypt_method, $key, 0, $iv);
    }

    return $output;
}

$info = "mysecret";
$encInfo = bad_crypt($info);

echo "encrypted:";
echo "<br>";
echo $encInfo;

echo "<br>";
echo "<br>";
echo "<br>";

$t = bad_crypt($encInfo, "d");

echo "decrypted:";
echo "<br>";
echo $t;
?>

which gives the following output:

key:
3d13b07f244861f2d323d1734d773ce4bd079e2c17deb5695911e1387e0b579a
iv:
d9ec53dadaf1e968
encrypted:
QVBBaDcrdkRUdVFqZDV5cGFMNHJCdz09


key:
3d13b07f244861f2d323d1734d773ce4bd079e2c17deb5695911e1387e0b579a
iv:
d9ec53dadaf1e968
decrypted:
mysecret

I have tried numerous combinations of options for openssl; none did reproduce the PHP encryption result or decrypted it.

Example openssl encryption command:

openssl.exe enc -e -aes-256-cbc -a -K 3d13b07f244861f2d323d1734d773ce4bd079e2c17deb5695911e1387e0b579a -iv d9ec53dadaf1e968 -in mysecret.txt

with mysecret.txt containing mysecret results in plQ2hEAoywxUeFWniDszdQ==.

Any help is appreciated.
Looking forward to a working openssl cli command and a C# program.