Hi @hudson,
Welcome to the Auth0 by Okta Community!
You can debug your action script logs to verify the behavior using Real-time Webtask Logs Extension. We recommend also using console.log() statements to debug.
We also strongly recommend using namespace custom claims. This is typically a best practice because, in the case of collisions, the transaction won’t fail, but your custom claim won’t be added to your tokens, which could be your issue. There is some documentation linked that can be helpful.
Hope this helps!