Battle Standard will not cast Smite on Lagon unless the Battle Standard is thrown into Lagon. See here: https://imgur.com/a/uoUaZ9W
Related: Battle Standard can seemingly be thrown anywhere, including off the edges of bridges or onto mountains/rocks, etc. Can’t lunge to it, but lose the buffs when this happens.
That is frustrating, this is a known issue. We are working to resolve this but it is a complicated problem with how the boss is off a ledge and how abilities pick targets. It will take some time to address how to approach this issue.
I remember one of the bosses in the SWTOR raid Terror from Beyond had a kinda similar set up with players on ledges but still needing to be able to hit the boss with melee skills. In order to get around that the zone had a “buff” which significantly increased the range in which a skill concidered the target to be valid. Perhaps something similar could work for Lagon?