Is there a support contact or developer forum for the Advertising API (https://advertising.amazon.com/API/docs/v2/guides/get_started)?
The documentation doesn’t have any references to a place to get help.
There is a Jira account that you can raise issues on. Unfortunately, I think you need to request access somehow. Newly registered accounts get an automatic invite, but if you’ve had an account for a while you might have not been invited. I really had to push to get in.