Unable to upload Excel data via API

Hello everybody,

I am trying to programatically upload an Excel file (could also be a JSON file) to a workspace using the API but I can't seem to make it quite work.

I am using the endpoint as specified at https://docs.microsoft.com/en-us/rest/api/power-bi/imports/post-import-in-group where the phrasing leads me to believe it should be possible to import Excel files this way.

Sample C# code used :

public bool ImportExcelFileToWorkspace(string filePath, string filename, string displayName)
        {
            var req = new HttpRequestMessage(HttpMethod.Post, $"https://api.powerbi.com/v1.0/myorg/groups/{Context.GroupId}/imports?datasetDisplayName={displayName}");
            var content = new MultipartFormDataContent();
            Stream fileStream = File.OpenRead(filePath);
            content.Add(new StreamContent(fileStream), displayName, filename);
            req.Content = content;
            Credentials.ProcessHttpRequestAsync(req, CancellationToken.None);
            var message = Client.HttpClient.Send(req);
            return message.IsSuccessStatusCode;
        }

I am using a class with a Credentials fields that uses the .NET API Connector and auth is fine.

Both the filename and displayname variables feature the file extension.

Using this method, I am being return an error 400 Bad Request with detail "ExcelWorkbookHasNoDataException" which is false.

Has anybody successfully used this endpoint like I am intending ? Any insight as to what I might be doing wrong ?

Thank you all in advance !