Until recently, presumably before Safari 12, it was possible to Option-drag individual bookmarks folders to and from Safari’s Sidebar or Bookmarks window to copy them from or to elsewhere. I find this no longer possible; if I try it now, the usual +sign-arrowhead combo appears with the Sidebar (the Bookmarks window is ‘dead’ in this respect), but ‘dropping’ the 'load' doesn’t produce anything.

If I’m wrong. and this feature wasn't removed, how is it done now? I’m NOT referring to Safari's bookmarks export option under the File menu (Export Bookmarks).

It works for me in Safari 12.0.1 under MacOS 10.14.1 beta 2. My perception is click and drag actions are finickier than I recall in previous OS versions whether you are in Safari or Finder, or pretty much whereever — which is not surprising as they all use the same APIs. During the MacOS 10.14 beta I adapted to a distinct two step process...

1. Select the item to be moved and be sure it has been selected (background color change, etc.)
2. Put the pointer on the selected item THEN click and drag.

…for me that works reliably where the "grab and go" single step process is unreliable at the very best.

Thanks for looking at this, Joe. Here’s the problem for me: I cannot select Sidebar folders, as clicking them opens them*. I can select bookmarks folders in the main Bookmarks window, but they cannot be dragged. Dragging vertically simply adds to the selection. Btw, I’m running MacOS 10.12.6.

*) I can Option-drag them without selecting them, and when I do that, the green +sign-arrow combo appears, as mentioned above. But no copy is produced upon dropping, like it did in Safari versions before 12. To be clear: when I drag the +sign-arrow onto a folder, this gets selected and opens if I hover long enough. But no copy appears when I drop the 'selection'.

PS. 1. This happens on two different Macs, both running Sierra. 2. Disabling extensions doesn’t help.

Mojave/Safari 12.0, and I can successfully(*) drag(**) & drop bookmarks folders from both my sidebar and my bookmarks window to my desktop, BUT I'm unable to drop them into another folder or move my test items from my desktop to either another folder or the trash (The moves begin, i.e. the expected pop-ups appear, but are never completed.) without restarting, although I can "rm" them.

Moving individual bookmarks to either my desktop or a folder thereon works fine in all respects.

(*) Well...most times, but sometimes the drop doesn't complete, I'm left with a "ghost" folder on my desktop, and Safari becomes non-responsive, necessitating my force quitting it.

(**) A simple click and immediate [i.e. without releasing the click] drag works for me; no option-click required.