When lightning strikes a lightning rod that is either facing north, south, east, west it strikes the top of the block location and not the lightning rod it self.
Here is how it strikes.
[media]Here is how it should strike.
[media]Here is the offset that should be added on the Lightning Bolt entity so that it is placed correctly on the rod
North:
(x+0.5, y+0.625, z+0.13)
South:
(x+0.5, y+0.625, z+0.87)
East:
(x+0.87, y+0.625, z+0.5)
West:
(x+0.13, y+0.625, z+0.5)
Can confirm in 1.17.1.