Issues with dipole operator from FeynRules

Dear MadGraph team,

I have taken an existing FeynRules model (heavyN) and added dim-5 effective operators. Everything works fine until I add dipole operators:

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convert model /home/jjones/Programs/MG5_aMC_v2_9_2/models/heavyNeff5_all_UFO
import model heavyNeff5_all_UFO --modelname
compute_widths n4 --body_decay=3

Please note that the automatic computation of the width is only valid in narrow-width approximation and at tree-level.
INFO: load particles
INFO: load vertices
INFO: Get two body decay from FeynRules formula
Command "compute_widths n4 --body_decay=3 " interrupted in sub-command:
"compute_widths n4 --body_decay=3" with error:
SyntaxError : invalid syntax (<string>, line 1)
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in 'MG5_debug'.
Please attach this file to your report.
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The MG5_debug is not very helpful. It includes:
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Traceback (most recent call last):
  File "/home/jjones/Programs/MG5_aMC_v2_9_2/madgraph/interface/extended_cmd.py", line 1541, in onecmd
    return self.onecmd_orig(line, **opt)
  File "/home/jjones/Programs/MG5_aMC_v2_9_2/madgraph/interface/extended_cmd.py", line 1490, in onecmd_orig
    return func(arg, **opt)
  File "/home/jjones/Programs/MG5_aMC_v2_9_2/madgraph/interface/master_interface.py", line 346, in do_compute_widths
    return self.cmd.do_compute_widths(self, *args, **opts)
  File "/home/jjones/Programs/MG5_aMC_v2_9_2/madgraph/interface/madgraph_interface.py", line 8520, in do_compute_widths
    value = eval(expr,{'cmath':cmath},data).real
  File "<string>", line 1
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Then comes a long line of code involving the coefficient of the dipole operator, I copy a short part of it:
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 ((mdl_mN4**2 - mdl_MZ**2)*((mdl_ee**2*mdl_mN4**2*mdl_VeN4**2)/(2.*mdl_cw**2*mdl_sw**2) + (mdl_ee**2*mdl_mN4**4*mdl_VeN4**2)/(2.*mdl_cw**2*mdl_MZ**2*mdl_sw**2) - (mdl_ee**2*mdl_MZ**2*mdl_VeN4**2)/(mdl_cw**2*mdl_sw**2) + (2*mdl_alphaNB4e*mdl_ee*complex(0,1)*mdl_mN4*mdl_VeN4*complexconjugate(Sig(Index(Lorentz,mu$11095),Index(Lorentz,PRIVATExeext(2))))*FV(2,Index(Lorentz,mu$11095))*FV(2,Index(Lorentz,PRIVATExeext(2))))/mdl_cw - (2*mdl_alphaNB4e*mdl_ee*complex(0,1)*mdl_mN4**3*mdl_VeN4*complexconjugate(Sig(Index(Lorentz,mu$11095),Index(Lorentz,PRIVATExeext(2))))*FV(2,Index(Lorentz,mu$11095))*FV(2,Index(Lorentz,PRIVATExeext(2))))/(mdl_cw*mdl_MZ**2)
****

It then finishes with:
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SyntaxError: invalid syntax
Related File: <string>
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And I am stumped. I have adapted the dipole operator from the BSMC_v2.2.fr file of the BSM Characterisation model in the FeynRules page, so I really do not know what I am doing wrong.

This might be a long shot, but could it be a MadGraph issue related to the Majorana nature of the neutrinos?

Many thanks for your attention.