If you are having issues with the API and suspect it is a bug, the following template can help us to help you by ensuring we have the right information. We also have a page with API troubleshooting advice that might be useful.
API support template
On which version of Totara are you seeing this issue (include major and minor version, e.g. 17.1)?
Does your Totara site have any local customisations? If so, please describe them.
Please provide a copy of the exact request you are making that is not responding as you would expect.
Please provide the exact response you are receiving.
Please provide details on how the response differs from what you would expect to receive (e.g. what the problem is).
If the issue relates to performance, please provide information about the response time, any error messages in the API response or server logs, and any other server diagnostic information you have available.