I could download the .xlsm file individually but when I tried to download them as ZIP. It says ‘The file is corrupt and cannot be opened’. This is happening only for the .xlsm files but not while downloading .csv files as ZIP

Server-side API controller

public async Task<IActionResult> DownloadZIP([FromBody] List<SomeList> req)
{
     List<string> pathLists = new List<string>();
     // From the req getting the file paths
     pathLists.Add(filePath);
     
     try
     {
        // if pathLists null, return from there
        Stream streamZip = await Task.Run(() => someServer.ConvertToZIP(pathLists));
        return File(streamZip, "application/zip", "file_name.zip");
     }
     catch (Exception ex)
     {
        // Handle exception and return
     }
}

Server-side service API

public Stream ConvertToZIP (List<string> pathList)
{
    var memoryStream = new MemoryStream();
    using (ZipArchive zipArchive = new ZipArchive(memoryStream, ZipArchiveMode.Create, true)) 
    {
        pathList.ForEach(filePath =>
        {
            string fileName = Path.GetFileName(filePath);
            var demoFile = zipArchive.CreateEntry(fileName);
            var stream = CreateStream(filePath, FileMode.Open);
            var reader = new StreamReader(stream);
            var entryStream = demoFile.Open();
            using (var streamWriter = new StreamWriter(entryStream))
            {
               streamWriter.Write(reader.ReadToEnd());
            }
        });
    }
    memoryStream.Position = 0;
    return memoryStream;
}

Client side

downloadZIPFile() 
{
    someService.DownloadZIP(this.createList()).subscribe(res => {
       if (res) {
           var binaryData = [];
           binaryData.push(res);
           var url= window.URL.createObjectURL(new Blob(binaryData, {type: "application/zip"}));
           var link = document.createElement('a');
           link.href = url;
           link.download = "filename.zip";
           link.click();a
       }
    });
}

Client service

DownloadZIP(req: someEvents[]) : observable<Blob> 
{
   let dowloadAPI = "someapi/some/some";
   const httpOptions = {
      responseType : 'blob' as 'json';
      headers: new HttpHeaders({
         // type as 'text/csv' also not worked
         'Accept': 'application/vnd.ms-excel.sheet.macroEnabled.12'  
      })
   };
   return this.http.post<Blob>(downloadAPI, req, httpOptions);
}

The file size is same both at the server and client side. What am I missing?