Dragging messages to another folder worked fine until today. Today, I tried to drag a message to a folder and it did not move the message. I tried this with several folders and several messages. Restarting with add-ons disabled (safe mode) did not solve the issue. I then restarted in regular mode and dragging now works. I restarted again in regular mode and it is still working. So, I have no problem now, but I noticed there were several other similar issues posted and wanted to add this in case it is helpful in understanding that there may still be a lurking problem. Thanks for an excellent mail client!