Additional note to @dalelear
I checked similar model and it is not working properly either, but it was working properly in the previous SR one week ago.
Sorry, I broke ToNURBS in this week’s WIP release. It is fixed in 6.12, 6.13, and 7.0 when the version date is on or after Dec 13, 2018. This is the what I’m getting in (7.0.18347.10465, 12/13/2018).