Hello @olaskole4405,
Welcome to the Auth0 community!
What might be causing your issue is that you registered your API as a Regular Web APP. You can try registering it as an API: Register APIs.
After doing that, you should select your API and go to settings. There, you have to scroll down to the bottom of the page to Access Settings and make sure Allow Offline Access is toggled on.
The following Knowledge Solution explains using Refresh Tokens for a SPA: How to Use Refresh Tokens in a SPA?
For more information about Refresh Tokens make sure to check the documentation: Refresh Tokens
I hope this was helpful and don’t hesitate to ask more questions.
Thanks,
Tudor