i've tried the latest sourcetree version and older one 220.127.116.11
the same issue with both version - see attached/embedded screenshot below
the pop-up labeled (P) keeps coming up!
i am using the same credentials that lists the 2 repositories in the top/1st screenshot.
You need to upgrade your Git Credential Manager (GCM) for Windows version.
The GCM is bundled with Git for Windows. If you are using a System Git install you can upgrade to Git 2.20.1 or higher alternatively upgrade Sourcetree and then update the Embedded Git.