The Share menu item has never worked outside of Explorer. It looks like Microsoft wrote it in a way that it only works in one place, and they hide it everywhere else (e.g. File > Open in Notepad).
(Update: Yes, looking into it in more detail, it looks like the Share context menu item just pushes a button on Explorer's ribbon toolbar, which obviously won't work anywhere else. I don't know why MS would implement a context menu extension this way as it isn't correct.)
For some reason it's showing up in Opus again, so we probably need to adjust the way we block it from our menus.
You can still share folders via right-click > Properties > Sharing.