projectile hit event occurs when it hits the ground and when it hits a player, you can try to merge it with Prohectile Damage Player event to check if it didn't hit a player (maybe give it a variable (not a tag) on Projectile Damage Player event and wait 0 ticks on the projectile hit, if the variable is 1 then it hit a player, after you check, don't forget to use Set Variable Purge so you don't have useless variables, also, the variable should be %uuid not %projectile cuz name overlap ;-;)