TaskCanceledException in call ListFolderAsync("/Image/") with app xamarin portable

Below is the code, in project ConsoleApplication works perfectly, but cross platform occurs the error.
I would like to know if someone has already used the ListFolderAsync api in poject portable (cross platform) with Xamarin Android?

Code:

private async void OnDownloadListaClicked()
{
var _accessKey = "<REDACTED>";
using (DropboxClient client = new DropboxClient(_accessKey))
{
//this.ListRootFolder(client);
try
{
bool more = true;
var list = await client.Files.ListFolderAsync("/Image/");
while (more)
{
foreach (var item in list.Entries.Where(i => i.IsFile))
{
// Process the file
}
more = list.HasMore;
if (more)
{
list = client.Files.ListFolderContinueAsync(list.Cursor).Result;
}
}
}
catch (Exception ex)
{
// Process the exception
}
}
}