Unexpected error and output from Element.SetParameterByName

Hi;
I get the error
Warning: Element.SetParameterByName operation failed.
The parameter is read-only.
Does this mean that we can’t push parameter values into nested families?
Also, The List generated by the same node shows data from a field that I didn’t index. Are the problems related.


The desired fields DID populate with suitable data, despite what the List shows…