Logout from all Stack Exchange accounts, open:
After login, I got the Stack Exchange home page instead of careers.stackoverflow.com.
Sorry about that. Turns out, return URLs were broken on stackexchange.com entirely during signup and login. A fix is out now, so any API app auth redirect issues should also be resolved with it.
Please let me know if you see any other problems. Thanks for the report, and my apologies for the delay in fixing the issue.