Has any progress been made on this issue. We are experiencing it in 4.18.
Unchecking LockSource and LockTarget in the source and the target module is a workaround, but unfortunately it is not an opportunity for me 
Epic, please show a minimum of grace and solve this issue. There is no Niagara.
That does not work for me.
See UE-61695 for the corresponding bug report. The announcement for UE 4.20 Preview says “Niagara is now available as Early Access.” So I don’t think that this issue will be fixed.
That’s why I am still interested in a workaround, but I am nearly sure that there is none.