Compex_mass_scheme and dim6top model

Dear experts,

I am trying to add EFT effects to the particle decay in the dim6top model. My understanding was that this should be done in the complex mass scheme to account for the changes in width due to the EFT effects. Hence, I'm trying

import model dim6top_LO_UFO
set complex_mass_scheme True
define p = p b b~
generate p p > w+ b j $$ w+ w- z a DIM6=2 FCNC=0 QED=3 QCD=0, w+ > l+ vl
add process p p > w- b~ j $$ w+ w- z a DIM6=2 FCNC=0 QED=3 QCD=0, w- > l- vl~
output pn

However, the "output pn" command crashes with the following log:

Error detected in "output pn"
write debug file MG5_debug
If you need help with this issue please contact us on https://answers.launchpad.net/mg5amcnlo
MadGraph5Error : Unable to evaluate mdl_vev = 1./cmath.sqrt(mdl_Gf*mdl_sqrt__2): raise error: name 'mdl_Gf' is not defined

Is the CMS supported then? What is the proper way to use it?

Thanks in advance,
Sergio