You can reduce effect by increasing the ‘Cloud Threshold Distance’ to a value greater than 0, 0.1 should work.
As for the Niagara, we’ve figured out where the problem is, however since it’ll require direct changes to UE4 it may take some time to actually implement a fix, since some changes will have to be made on Epic’s side to make sure that people using the binaries version of the plugin can still use the two plugins alongside each other.