The GitHub Repository Feed works as expected when I enter the personal access token manually.
I would prefer to be able to select the access token I previously defined in Accounts -> Tokens (see picture below) from a dropdown instead of typing the access token manually.
Thanks for getting in touch and sorry for the delayed reply.
This was a conscious decision at the time. We tend to avoid using accounts linked to feeds, since feeds need to be accessible outside the environment.
For example, token accounts can be scoped to environments (not mandatory, but you can scope an account to one or many environments), so we felt it could quite easily create a problem if an external feed was referenced in a step deploying to EnvironmentA, but the token account that the feed is referencing was scoped only to EnvironmentB.
So to avoid any potential confusion, we kept this as a separate/independent token field on the external feed.
While it would be handy to centralise this token and manage it via accounts, we decided against this approach to reduce the potential for scoping clash/confusion.