I have configured Thunderbird to use Box for FileLink. But when I try to use FileLink, it won't actually upload a file to Box. It just sits there with the little spinning icon for hours. I manually added a file to Box and then looked at the setting in Thunderbird. There I could see the space being used by the file I added. Therefore, it looks like Thunderbird is communicating with Box. So why don't files upload from within Thunderbird?