I was recently updating some of my Personal/Public Unity Libraries. I use SourceTree for most of my GIT work. One, because I am old, and don't like using the command line much anymore, and two because they have a really slick interface for using the GitFlow methodology, which I "try" to follow.
So, I tried to initialize the GitFlow for the project folder, but alas, I was missing my MASTER branch. I had removed it after pushing my DEVELOP branch to GitLab.