Have you tried using the event BeginOverlap instead?
Get the HitActor and make sure it’s valid to prevent errors, if it’s valid - try and cast it to whatever you’re trying to hit, for example MyCharacter. If the cast succeeds, this means the projectile’s collision has begun overlapping with the character*(make sure the checkbox to generate overlap events is checked)*. And in doing so you can apply damage or whatever you want to do, might also want to remove the projectile or it’ll pass through.
Default collision for the static mesh should do just fine.
Thank you so much @Blue_man ! Setting the sphere collision component as the Scene Root and then using Event Hit rather than Event ActorBeginOverlap solved the issue of projectiles going through walls and landscape meshes.