Why is my Multipart Form not working when sent from .NET Framework 4.6.2?

Question

I currently have 2 APIs. One is in .NET Framework 4.6.2 and one is in .NET 8.

I'm trying to upload files and metadata as form-data though the .NET Framework API to the .NET 8 API. When uploading form-data through Postman or JavaScript directly to the .NET 8 API, it receives the files and stringified metadata perfectly fine. However, when trying to go through the .NET Framework API, no content ever shows up in the .NET 8 API.

Here is the endpoint for the .NET Framework API to read in the form data.

[HttpPost]
[Route("Route")]
public async Task<IHttpActionResult> UploadMultipleOrderForms() {
    var provider = new MultipartMemoryStreamProvider();
    await Request.Content.ReadAsMultipartAsync(provider);
    List<Stream> files = new List<Stream>(); // I also tried this as byte[]
    List<string> metadatas = new List<string>();
    foreach (var part in provider.Contents) {
        var name = part.Headers.ContentDisposition.Name.Trim('\"');
        if (string.IsNullOrEmpty(part.Headers.ContentDisposition.FileName)) {
            var fieldData = await part.ReadAsStringAsync();
            metadatas.Add(fieldData);
        }
        else {
            var fileData = await part.ReadAsStreamAsync();
            files.Add(fileData);
        }
    }
    return Ok(await UploadMultipleFiles(
        files,
        metadatas,
        "azure-container",
        Request.Headers.Authorization.Parameter
    ));
}

Here is the function that calls the .NET 8 API.

public async Task<IEnumerable<object>> UploadMultipleFiles(
    IEnumerable<Stream> files,
    IEnumerable<string> metadatas,
    string containerName,
    string jwt
) {
    var client = new HttpClient();
    client.BaseAddress = new Uri(_dotnet8ApiUrl);

    var form = new MultipartFormDataContent();

    foreach (var stream in files) {
        var streamContent = new StreamContent(stream);
        streamContent.Headers.ContentType = new MediaTypeHeaderValue("image/png");
        form.Add(streamContent, "files", Guid.NewGuid().ToString());
    }
    foreach (var metadata in metadatas) {
        form.Add(new StringContent(metadata), "metadatas");
    }

    client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", jwt);

    var response = await client.PostAsJsonAsync(
        $"UploadEndpoint/{containerName}",
        form
    );

    return new object[] { response };
}

Here is the function signature for the .NET 8 endpoint.

[HttpPost("UploadEndpoint/{containerName}")]
[AllowAnonymous]
[ProducesResponseType(StatusCodes.Status201Created)]
[ProducesResponseType(StatusCodes.Status500InternalServerError)]
public async Task<ActionResult> CreatBlobsAsync(
    [FromForm] IEnumerable<IFormFile> files,
    [FromForm] IEnumerable<string> metadatas,
    [FromRoute] string containerName
) {
    ...
}

No matter what I try, both files and metadatas are null in the .NET 8 API when sending like this.

Any help is appreciated! Any other improvements that could be made are also appreciated.

Thanks!