ApplicationIntegrations create_notification not working

[rmunoz10]

Hello,
create_notification works in Postman using correct parameters for the sandbox but does not work in the API using the same parameters. Attached image shows successful run using Postman.
Not sure what I may be missing.
Thanks

Environment: Ubuntu 24.04 LTS.

*** ERROR ***

Exception has occurred: SellingApiBadRequestException
[{'code': 'InvalidInput', 'message': 'Could not match input arguments', 'details': ''}]
File ".../main.py", line 141, in
res = client.create_notification(body = data)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
sp_api.base.exceptions.SellingApiBadRequestException: [{'code': 'InvalidInput', 'message': 'Could not match input arguments', 'details': ''}]

*** TO REPRODUCE ***

_API_REFRESH_TOKEN='xxxxxx'
CLIENT_ID='xxxxxxxx'
CLIENT_SECRET='xxxxxxxxxxxxxxxx'
AWS_ACCESS_KEY='xxxxxxxxx'
AWS_SECRET_KEY='xxxxxxxxxxxxxxxx'
BASE_URL='https://sandbox.sellingpartnerapi-na.amazon.com'

CREDENTIALS = dict(
refresh_token=_API_REFRESH_TOKEN,
lwa_app_id=CLIENT_ID,
lwa_client_secret=CLIENT_SECRET,
aws_access_key=AWS_ACCESS_KEY,
aws_secret_key=AWS_SECRET_KEY,
)

client = ApplicationIntegrations(
credentials=CREDENTIALS,
)

client.endpoint = BASE_URL
data = {
"templateId": "PRICE_CHANGE",
"notificationParameters": {
"priceValue": "200"
},
"marketplaceId": "ATVPDKIKX0DER"
}
res = client.create_notification(body = data)

*** POSTMAN WORKS ***
https://sandbox.sellingpartnerapi-na.amazon.com/appIntegrations/2024-04-01/notifications

body
{
"templateId": "PRICE_CHANGE",
"notificationParameters": {
"priceValue": "200"
},
"marketplaceId": "{{marketplace}}"
}