Using Github Desktop, cloned repository, updated it, went to push, got popup "Authentication failed. You may not have permission to access the repository or the repository may have been archived. Open options and verify that you're signed in with an account that has permission to access this repository".
Clicked File, clicked Options, got popup showing me logged into my one and only relevant account, which the superuser tells me is authorized to access.
Superuser sends new invite to join the repository. I accept. See message "You now have push access to XYZ repository", i.e., the one that failed above.
Attempt push, same failure.
Check File/Options, same account.
What might explain the push failure?