Recently it happened every time I tried to download multiple media on a page. On Firefox "Page Info > Media", I selected a batch of media files, say pictures in .jpg format and clicked "Save As". I was prompted for file folder. After selecting the folder, the batch of media files were not downloaded to the folder. As I exited Firefox, I was prompted whether to stop the downloading. Weeks ago, the selected batch of files would be downloaded immediately as I clicked "Save As". (Environment = Firebox 84.0.2 (64 bites) on Windows 10)