I know this thread is old, but I am having the same problem. I never remember this problem with 4.21.6, so maybe I just need to go back. The problem with the last reply is that files never starts downloading again. They just await sources. Only about 10 percent of the time has it said the file was already downloaded and asked me if I wanted to append. Most of the time the downloads never even restart. I can go to library or the incomplete folder and play with no problem. I can't even preview on the download screen after attempting to restart. But I can cancel the file and just restart the same download with no problem