I am relieved this was fixed. I was losing my mind. I did a complete uninstall of CdB and add-ons, including manual removal of files and registry entries, and turned off every firewall and antivirus I could think of. I ran Assistant in Admin mode, as is often advised, and encountered most of the issues reported here--download doesn't start, or it completes but installation doesn't start, etc. In the end I managed to install CdB, SI, Drum Replacer, and Melodyne--I have no use for Theme Editor--but I had to do it incrementally, on piece at a time, over a 24 hour period. I was hugely relieved to see things back to normal, and felt vindicated when the CdB group on Facebook directed me here. At least I had the sense to back up and later restore my VST folders, so all of that is back in order without having to do full reinstalls of every 3rd party plugin. Lesson here? Next update I DON'T uninstall anything, and if Bandlab Assistant downloads are wonky I must be patient because I most likely has nothing to do with anything on my end.