Try another way to get person name.

biscuit/apps/alsijil/forms.py

@@ -18,8 +18,8 @@ class PersonalNoteForm(forms.ModelForm):
     person_name = forms.CharField(disabled=True)
 
     def __init__(self, *args, **kwargs):
-        kwargs.update(initial={'person_name': str(kwargs['instance'].person)})
         super().__init__(*args, **kwargs)
+        self.fields['person_name'].initial = str(self.instance.person)
 
 
 PersonalNoteFormSet = forms.modelformset_factory(