Hi James,
The auth issue started happening as soon as we permitted developer permissions. We needed to do this, as you say, to grant the correct scopes, but this hasn’t fixed to auth problem. This was / is an old private app and we haven’t changed anything around the keys, but I’m guessing something changed with it’s permissions. Do you have a migration plan at all? Is there something we need to do to just get the current app back up and running?
Is it no longer possible to run these requests using Postman, or is there a collection I can download from somewhere?