It seems random that RTL won’t hit the target where it should.
This bug can happen quite often and unexpected.
The mob stands stationary and is WITHIN range and not doing any dodging, etc., but RTL will keep playing the lightning animation at the target’s location and at the end still won’t hit, resulting in 40 second cool-down.
It seems this bug can happen on any mob.
So far hasn’t got issue in PvP or WvW.