Loss of damage from the electric ball

Sometimes when I use the ball to attack the elite monsters, the monsters don't lose any health points.

Is this for PoE 1 or PoE 2? You posted in PoE 1 bug reports, but Ball Lightning typically has good damage in PoE 1 so sounds like a build issue if PoE 1.

If this is PoE 2, the base damage of Ball Lightning is very, very bad and made worse because it has a range of 4-70 at level 20 so you can low roll repeatedly. Most of the damage is coming from slow moving balls that can hit repeatedly plus the explosion damage when infused.

I have no good recommendations for PoE 2 Ball Lightning other than you need to post in PoE 2 suggestions forums and there are a lot of skills with very bad balancing. Arc/Spark/OoS seem be the 3 main lightning spells I see people use with Ball Lightning used for shock/exposure generation or the Lightning Warp tech.