Finding Boss Coordinates

[Kalinfe]

Is there any specific way to find boss coordinates of a known unitId or unitTag? I note there is the function GetUnitWorldPosition(unitTag) but reporting from this returns 0 in both x and y when used with the tag 'boss1' or 'boss2'. I'm trying to make an addon that tells people where a certain boss teleports to so they are more quickly able to react.

Anyone else encountered an issue like this? Would putting in the unitId work instead?