update many custom org feilds via API suceeding but not updating data in sandbox

Hi,

We added two new custom org fields and have tens of thousands of records to update. I don't want to do them 1999 at a time using the bulk update functionality, so I was trying to test an update many through the API. The below block succeed, but I did not see either field update in our sandbox. I also tried making the list of updates a value for custom fields in a dictionary as a value for the organizations dictionary, but received a parameter error. Do I have this structured properly? Am I calling the custom field names incorrectly? Am I doing something dumb, like the Ids should be strings? The API documentation isn't really helping at this point.

curl --location --request PUT 'https://company_sandbox.zendesk.com/api/v2/organizations/update_many.json' \
--header 'Authorization: {AUTH}
--header 'Content-Type: application/json' \
--header 'Cookie: {Cookie}
--data-raw '{
"organizations":  [
 {"id":1500479850061, "sugar_system_id":"000-001", "sitename":"Data"},
 {"id":1500479850141, "sugar_system_id":"000-002", "sitename":"Data"},
 {"id":1500479850281, "sugar_system_id":"000-003", "sitename":"Data"}
]
}
'