When I have several windows within a group, sometimes I'd prefer a particular window to be closer to the panel, so I'd like to reposition it within the group. The item will drag, but it can only be dropped on a panel to create a launcher.
This is a regression, confirming.
Fixed by https://cgit.kde.org/plasma-desktop.git/commit/?id=7db2a6fbe394326777a771b9461b989606a6a2fa