Python Platform SDK: Bulk user creation from CSV failing with 400 Bad Request

I’m writing a script to bulk-create users from a CSV using the Genesys Cloud Python Platform SDK. I’m iterating through rows and calling users_api.post_users(). The first user creates fine, but subsequent calls return 400 Bad Request with "message":"Validation failed". I suspect it’s a rate limit or payload issue. Here’s the snippet:

for row in csv_rows:
 body = CreateUserRequest(**row)
 users_api.post_users(body=body)

What am I missing?