Thumbnail doesn't appear for Flickr ECL Components

Question

I was trying to implement Flickr ECL, using extension and configured in my Tridion.

Images and Albums are reflecting in Tridion, but thumbnail images are not working properly, I see a blank image.

On Folder View

ECL Component View

I have debug on GetThumbnailImage method it is working fine, cleared cache many times but still I was getting blank.

Update:

I tried to inspect img(blank) in Component view, it was pointing to http://localhost/WebUI/Editors/Base/icon.png?target=view&maxwidth=320&maxheight=200&uri=ecl%3A9-flickr-38587920765_b15971826b_72157690242528371-img-file&modified=20180104062538&state=ecl%3AFile.L0P0

GetThumbnailImage code

public byte[] GetThumbnailImage(IEclUri eclUri, int maxWidth, int maxHeight)
{
    // only return thumbnails for the actual photos
    if (eclUri.ItemType == EclItemTypes.File && eclUri.SubType == "img")
    {
        // format of photo item id: [flickr photo id]_[flickr photo secret]_[flickr photo set id]
        string[] ids = eclUri.ItemId.Split('_');
        FlickrInfo photo = Provider.Flickr.GetPhotoInfo(ids[0], ids[1], ids[2]);

        WebClient webClient = new WebClient();
        byte[] thumbnailData = webClient.DownloadData(Flickr.GetPhotoUrl(photo, maxWidth));
        using (MemoryStream ms = new MemoryStream(thumbnailData, false))
        {
            return Provider.HostServices.CreateThumbnailImage(maxWidth, maxHeight, ms, Flickr.MaxWidth, Flickr.MaxHeight, null);
        }
    }
    return null;
}

Answer 1

I want to start by saying that this doesn't have to be only code/tridion issue. For example, we had similar issue with our thumbnail icons where they weren't downloaded also from media manager. In our case, we observed that thumbnails aren't downloaded even with correct connection to Media Manager. We were debugging this for days with SDL customer support, only to find out that there was firewall issue. :) Some of the traffic was blocked by firewall, so thumbnails weren't downloaded in correct folder in tridion. So please try to investigate with Infra team if there is some network blockage. This might fix the problem.