Auth0 and Air - invalid authorization code

Hi folks.
Using Auth0 from with an Air app (in a stageWebView) - doing so with the " Add Login to Native/Mobile Applications" workflow.

All seems good generating the code verifier and challenge, going through the first hurdel of the authorize redirect and extracting the authorization code.

However, no matter what I do with submitting the code_verifier along with the auth code to the /token endpoint I cannot get an athorization token. It’s saying my auth code is invalid.

Has anyone had any experience of auth0 from an air app /as3 or mobile devices/standalone native apps and had similar issue?

Does anyone know how I can eek a few more clues out of Auth0 (just get a a failed exchange in logs)?

It’s frustrating as the docs are really good - it just doesn’t want to do what it says on the tin.

Did you have any luck? I might be trying to implement this soon.
Did you try with a normal stagewebview, or an ane like distriqts NativeWebView?