Fixes #6908: Allow assignment of scope to VLAN groups upon import

netbox/utilities/forms/fields.py

@@ -269,6 +269,8 @@ class CSVContentTypeField(CSVModelChoiceField):
         return f'{value.app_label}.{value.model}'
 
     def to_python(self, value):
+        if not value:
+            return None
         try:
             app_label, model = value.split('.')
         except ValueError: