hello, I found an error in the niagara components added to a blueprint. when you create a niagara component in an blue print actor, if your niagara system have an exposed parameter skeletal mesh, if u try to modify any parameter, the UE4 engine broke. i used my own systems and the default systems and the result its the same. If u do an innerit blueprint the system works fine but its a problem if you cant do your own blue print. In Visual Studio you can see an SystemInstance NULL then broke. Line 1207 SystemInstance->Reset(FNiagaraSystemInstance::EResetMode::ResetAll, true); on NiagaraComponent.cpp