.NET Core Created Zip Archive is corrupted

Question

I'm creating a web api route that takes a list of byte arrays and creats a zip file out of it. However the returned file is corrupted and im unable to extract it's content using a Windows default zip extractor (I'm able to open and extract it correctly using 7-zip however). What could be a possible reason for that?

 using (var stream = new MemoryStream())
 using (var zipArchive = new ZipArchive(stream, ZipArchiveMode.Create))
 {
   var i = 1;
   foreach(var file in files)
   {
     var zipEntry = zipArchive.CreateEntry($"{i}.txt");

     using (var zipStream = zipEntry.Open())
     {
        zipStream.Write(file, 0, file.Length);
     }
     i++;
  }

stream.Seek(0, SeekOrigin.Begin);
return new FileContentResult(stream.ToArray(), "application/octet-stream") { FileDownloadName = "Splitted.zip" };

}

Could anyone guide me on what's I'm doing wrong, whilst I'm creating a zip archive?

Edit: I even tried creating a zip with a single text file containing a 'hello' string and it still failed to open:

[HttpGet]
[Route("asd")]
public IActionResult Getasd()
{
    using (var stream = new MemoryStream())
    using (var zipArchive = new ZipArchive(stream, ZipArchiveMode.Create))
    {
        var text = "hello";
        var bytes = Encoding.UTF8.GetBytes(text);

        var zipEntry = zipArchive.CreateEntry($"asd.txt", CompressionLevel.NoCompression);

        using (var memStream = new MemoryStream(bytes))
        using (var zipStream = zipEntry.Open())
        {
            memStream.CopyTo(zipStream);
        }

        return new FileContentResult(stream.ToArray(), "application/octet-stream") { FileDownloadName = "Splitted.zip" };
    }
}