Actually i have two FSMs affected.
Adding and removing an action from the first one did the trick.
However it doesn't work for the second FSM.
A noticeable difference with the first one is that this FSM is on a prefab and uses a template.
This prefab is placed in many scenes of the game (not instantiated at runtime), and each time one of those scenes is loaded the message "FSM updated..." shows up.
I edited the template, added and removed an action, saved the scene/project with no luck.
Unfortunately i can't share the project because of NDA.