I am using 4.15 and having a terrible time migrating assets into a project from other workshop type projects then trying to move them to proper place within destination project. I have learned to never try to move or rename folders within content browser as this will just result in a second folder being created and editor will not allow me to delete old one regardless of when or how many times i run fix redirectors tool. Renaming assets and moving assets and folder structures around content browser is broken. This is a huge problem since migrating assets also migrates their old folder structure and there is no clean way to place incoming assets where they need to be. problem becomes unmanageable when assets have a complex set of inter-relationships which are bound to break if one resorts to file system explorer to clean things up.