Comment 4 for bug 1988652

Sorry for the late answer on this.
Could you attach the model?

I guess that the issue is that the initialization of the loop fails for small mass due to some threshold. (like the code does not know if it is zero or not) Setting the mass to zero likely solves the issue or putting large. Changing the mass does not re-trigger the computation of non zero helicity/... so the code is likely going trough.

I have assign this to our loop expert who might have more precise insight.

CHeers,

Olivier