Blizzard have reduced the power of the 
Lightning Rod Elemental Shaman talent, as it was overperforming in AoE after the patch changes.
You may need to switch to the Totemic Hero tree and back to have the talent work properly at all.
With the changes made in patch 11.0.5 to increase the effectiveness of several Elemental talents and cooldowns such as Ascendance, the Lightning Rod talent greatly overperformed. With a hotfix that went live a little while ago:
- Elemental
- Lightning Rod now transfers 10% of all lightning damage dealt to Lightning Rod targets (was 20%).
This reduction should significantly reduce its effectiveness in AoE damage situations, and less so when fighting a single target.
This change may require Shamans who were online and using the Stormbringer hero talent tree to either log out and back in or swap to the Totemic hero talent tree and back to the Stormbringer hero talent tree for their Conductive Energy hero talent to properly work.