Github authentication is totally broken in Sourcetree 3.2.1 for OSX.
Using OAauth authentication, SourceTree will let you clone a branch, but after that reports "repository not found" when trying to push or pull to/from that branch.
Using basic authentication, even after saving password in SourceTree preferences/accounts, SourceTree asks for your password 3 - 5 timeswhen pushing or pulling. There is a "Save password in Keychain" checkbox, but this does not work.
We see you have a comment on a pre-existing post. We'll reference that post here to avoid duplication of the topic and help centralize feedback and updates. This post is a duplicate of the following: https://community.atlassian.com/t5/Sourcetree-questions/Sourcetree-for-Mac-GitHub-account-permissions/qaq-p/961120