Hi @dphilipson
Welcome to the Auth0 Community!
I am sorry about the delayed response to your inquiry.
If you are still facing issues with implementing a custom connection for Twitter (X), I believe the following knowledge article addresses the issue that you have stated in your post.
If you are still facing issues with the OAuth2 implementation for the custom Twitter social connection or have any other questions on the matter, feel free to leave a reply or post again on the community page. Otherwise, please let us know if the issue is already resolved.
Kind Regards,
Nik