Hi Claudio
I've had the same problem and had reported it to SAP - sorry, I didn't see your post earlier. They have confirmed that this is a bug and SAP will release a note - I will update this post when I get it. There is a workaround - the issue is that the form is expecting a custom field to exist, so the workaround is to create a custom field (and suppress it through configuration if it is not required), instruction link below.
Cheers
Daniel