Weird, yes. Sometimes migrating in a new project helps, in deleting unused parameters that could create issues.
Imo the line trace does fail due to collision meshes (weapon, skeletal mesh or world objects) and their respective scales.
And what about deleting and respawning a new charcter on level load (using post process effects to hide the thing) ? I guess you have some character informations you want to keep from one level to another, but this could be saved/loaded somehow…
Sorry I can’t help you more !