I am not sure how to format it for the field in the Live API, I vaguely recall that some of the Live API has some quirks. It referencing an Object, is due to it being an Object in the API, not necessarily passing an object through the Live API form, I could be wrong. I think the Live API is generated as part of the same process that generates the API documentation.
I tried passing this in the LiveAPI: {"enrollment_term":{"overrides":{"student_enrollment":{"start_at":"2021-06-03T07:00:00.000Z"}}}}
and got "message": "Invalid enrollment type in overrides"
I used PAW to format a JSON request payload that I was able to confirm updated the name of the term and the override
{
"enrollment_term": {
"name": "K12 20-21 Summer",
"overrides": {
"StudentEnrollment": {
"start_at": "2021-06-03T07:00:00.000Z",
"end_at": "2021-07-17T07:00:00.000Z"
}
}
}
}