A SUMMARY:
I have made some tests with archers recently and found a way to place archers on an elevated building piece (without stairs to the ground) so that they DO NOT TELEPORT TO THE GROUND, even if the line of sight with the target is interrupted or the target moves out of range or even out of render distance.
With the following test setup that works:
- Used archers can be mixed legacy or newer ones, levelled or not.
- All archers can have melee weapons and bows in the inventory, but it also works with bows only.
- It only works with platforms the size of a square foundation / ceiling or bigger, not with triangles or pillars.
- At the “Behaviour wheel”, I chose: “Attack distance”=max., “Chase Distance”=max., “Attack all”
- At the “Tactics wheel”, I chose: “Stand and Defend” (*)
- I tested this on PC official PVP during raid times, patch 07.05.2020, hotfix 08.05.2020 and 13.05.2020.
(*) As @Wak4863 pointed out, you can chose “prioritize ranged” first, and then “stand and defend” from the tactics wheel to make sure the thrall does not want to melee. Although it sounds strange to me, maybe it helps.