I just found out that the FirstPersonProjectile blueprint hit registration breaks as soon as I add another collision channel to the project (First Person project template).
Here are the steps to reproduce it: Create a clean new First Person project, go into your project settings, add a Object or Trace channel and set the default response to “Ignore”. Then play in PIE and shoot at stuff. The projectiles goes through everything and is not firing a hit event anymore.
Does anyone know why this happens or is that even intended? Looks like a bug to me.