Niagara's Initialize Particle Module has the Input.Position Write default Value False which is fine as long as the Cascade To Niagara Converter can realizes whether Cascade has the location Module and Switch the Position Write default True while doing the Converting
Create a Default Cascade Particle System, add a Initial location module and set the parameters a range of -200 -200 0 to 200 200 0; It should look like a sprites spraying from a square.
Convert this to Niagara, see the sprites spraying from a point. Look into Niagara modules, the Position parameter is disabled by default although those attributes has been converted
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-121602 in the post.