Go to the E_HitboxType it may also be called E_HitboxTypeAI in the Smart AI project files. Open it and make it look like the image below.
Next go copy the images below, the locations are at the tops of the images. You will be replacing the Apply Damage nodes with the Damage node and the Is Hitbox node with the Is Player Hitbox? node like the images show make sure you copy the images exactly and make sure you check the names of the node you are using to be sure they are the same as the images. You can delete the Apply Damage node and the old code that is no longer being used if you like.