Sometimes a Workflow Rule fails. How can I trace it? SM 9.34

Hello, in SM 9.34 is a behaviour that I'm trying to reproduce with not success yet.

In a Change Workflow (cm3r), a Rule sends a mail ¿when? in a phase, on update

The Rule description is :

Send HTML Email: TC_Change-Notificar Grupo Asignación (when (assign.dept in CurrentRecord!=assign.dept in SavedREcord))

I've looked at de emailout.log  for some errors, but nothing there.

¿Is there some way to trace or look at the CurrentRecord  and  SavedRecord  vars  to see why the condition fails sometimes / aleatory?

Thanks in advance,