Units lose health on Attacking

[Sorceress]

I'm working on a new LTW (Line Tower Wars) version, but suddenly I ran into a problem.
Some of my towers loses health when they are attacking enemy units.
But, it only happens when certain types of towers are created next to them.

Normal, without any upgraded towers:
https://i.imgur.com/4dSAZD2.jpg

With upgraded tower, suddenly they lose health on attacks:
https://i.imgur.com/Gs0lsnS.jpg

The units whos being attacked has no spells or upgrades.
The towers attacking are both using Frost Breath with splash damage, and i just ticked off 'Not self' on both attacks and spells to see if that would work, but it still happens.

Anyone who's got any idea?

 

[Tasyen]

"not self" is everyone else (except the caster/attacker), including allies and enemies. change it to enemies instead.

splash damage attacks have 2 allowed target Filters:

1. Allowed Attack targets
   
2. aoe Damage Filter,

 

[Sorceress]

"not self" is everyone else (except the caster/attacker), including allies and enemies. change it to enemies instead.

splash damage attacks have 2 allowed target Filters:

1. Allowed Attack targets
   
2. aoe Damage Filter,

Thanks, it was the "not self" being ticked under the aoe filter.