Since the begining, and after check everything... this skill stills bugged in some situations.

If you use it against a Dark Rift Boss to heal you during the battle, the orb does nothing.
The orb does not move around or follow you, and does not spam the healing aura.

And in other situations, like in a World Boss Area, this orb acts over everyone, not only your team or guild members.

Examples:

It has been more than 9 months since this error was noticed ... to this day the Shai healing orb still does not work in the Dark Rift Bosses.
The orb is expected to track party members (you included), and release a healing aura every so often.

In the video you can see that the orb remains motionless, waiting for something to do even though Ronin ends up killing me.