Hi @monochrome,
just wondering if you’ve seen the latest updates and if this eventually solved your issue? CORS config is in place for api.atlassian.com and you should be able to do your /GET calls. Unfortunately there’s still JIRA Cloud REST API (OAuth 2.0) Error 403 on POST Requests - #4 by sreuter that needs to be addressed for POST operations.
Thanks for bearing with us, we’re getting there!
Cheers,
Sascha