Not so much a bug, but more of an omission:
In the current version of MES (4.6R4), & for my Alfa Romeo 156 '02 GTA 3.2 V6, there is only one option of airbag ECU listed: "Siemens Airbag MY99".
This ECU does NOT connect in my car, or at least not without a warning ("wrong ISO code").
What DOES connect (fully) is this ECU: "Allied Airbag MY97," ECU ISO code A7 86 91 19 2C (as in the car model Alfa Romeo 156 1.6 TS 16V).
My car is 100% original as it left the factory, so the ECU cannot be a replacement unit.
You might want replace/append the Allied unit in the airbag ECUs offered for my model.