Metabox default field value does not work if one field in a metabox has a value set.
For example I have a field. I save the post. The field is now set in the DB.
I add a new field to the same metabox at a later time. The default (std) value for the new field does not load. The new field is always set to empty/''/0.
If I delete the original field value the new field (and the original) then show their defaults.