It's working as intended. It's unfortunate that the intended behavior is wrong, though.
When they were preparing for the launch of the world visit system, they removed the ability to target players by name for all commands except /tell. Only /tell accepts typed names as targets now, and even when sending a tell to someone on your own server you still have to include @World. Other slash commands can only take target tags. If you cannot see or target the other character model, you must use menus. This in itself would not be absolutely horrible, except that even when you can see the person's name in a list like /search, the blist command is often not included in the menu.
The system needs improvements.