Webinar participant registration - empty "registrants" field in response

API and Webhooks Webinars
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Format Your New Topic as Follows:

API Endpoint(s) and/or Zoom API Event(s)
POST /webinars/{webinarId}/batch_registrants

Description
*Sometimes the response body is missing approved registrants data, despite the fact the request was successful. We recieve a response with 201 status indicating that it was ok, but the registrants field(array) is empty.

The problematic users are included in the registration report, marked as approved, so I assume Zoom handles registering them correctly but fails to produce a proper API response(containing join_url). In effect, we cannot provide join_url to certain users and they cannot participate in webinars.
This strange behaviour happens rarely, I’d estimate in less than 1% of requests. *

Error?
There is no error, but the request body is missing registrant data like join_url, email and registrant_id

How To Reproduce
Steps to reproduce the behavior:
I assume you’d have to make several requests to register multiple participants and eventually you might stumble upon case where the response body does contains an empty registrants array.

Example webinar id were I experienced this issue: 93690309611
request: https://api.zoom.us/v2/webinars/93690309611/batch_registrants at 2022-09-14 08:50:41 AM(GMT+2)

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Turns out the API response will contain registrant data only if the user isn’t already registered.
In my case the user has already been approved via invitation sent through Zoom Portal and in effect the API response didn’t contain any info.

I guess it’s a bit confusing design that the HTTP status returned in such scenario is 201, and yet the response data is missing. Anyway the issue can be closed now.