IsoCurve Node issues

I am having some issues with the IsoCurve node. I have an older file that takes a point as an input (using  x,y, as u,v with z as 0) and returns both the U & V iso curves.  In a new file under 0.8.0066, the old node is still there (labeled as old) and works just fine, but when I add a new IsoCurve node and feed it a point (the same point) it fails to return the V iso curve (U iso curve is ok).  I've double checked the domain and the point contains valid UV coordinates...  Is this just a bug with the newer IsoCurve node?

In a related matter, how were isoCurve Nodes designed in regards to input points?  Is feeding them a 3d point is the correct way to use them? I couldn't find a way to create  a simple 2 pair coordinate...

Thanks,

tom