Thanks for the details, I was able to replicate the problem, but I’m not sure this is a problem with Testiny.
The issues.json URL seems to be accessible with and without an API key - just remove the API key and you will still get all issues. I have no idea how this is possible with Redmine, but it seems this is a sever security issue if your issues are not intended for the public.
What Testiny does to verify the Redmine connection is trying to access the my/account.json URL, i.e. for you: https://orch.redmine.com.chickenkiller.com/my/account.json
This page requires a valid authentication, so can you check this page with your API key please?
I have tried and it did not work, but you surely already reset your API key after posting it publicly in this forum, right?
Best regards,
Alex