Hello
If I uncheck "Include field prefixes" then  for example  " json.GetPropertyValue('Customer_Action',1) "  command does not work properly.
Therefore NetWebserviceMetrhod always tries to add a record even if the value of the "Customer_Action" is update.
This is because Customer_Action  is filled in code:
   If json.GetPropertyValue('Customer_Action',1) <> '' ! if the Action is not passed, then fall back on the REST http method.
      Customer_Action = json.GetPropertyValue('Customer_Action',1)
    ElsIf json.GetPropertyValue('action',1) <> '' ! if the Action is not passed, then fall back on the REST http method.
      Customer_Action = json.GetPropertyValue('action',1)
    End
I also noticed that almoust all fields with a "_" character cause problems when  "Include field prefixes"  is not true.
Only arrays works fine
Regards
Jari