waveguide model issue

[joamatab]

Im having some issues when using the waveguide model in scee with the simphony wrapper

The Sparameters seem to be almost zero for what I expect to be a critically coupled ring.

https://github.com/gdsfactory/gdslib/blob/master/gdslib/components/ring_single.py
https://github.com/gdsfactory/gdslib/blob/master/gdslib/components/ring_single_simpler.py

it's either coming from Simphony wrapper or from the scee waveguide model because when i replace the waveguide with the siepic waveguide it works, see

https://github.com/gdsfactory/gdslib/blob/master/gdslib/components/ring_single_siepic.py