I was working on a project inside Visual Studio Team Services and trying to create a new vNext build and was running into a problem where the "Default Agent Queue" dropdown was empty.
I had build administrator permissions for the project, so I should have been able to view the default agent queue and create the build. The Microsoft team changed the way the permissions work for creating builds. A user now needs be be apart of "Project Collection Build Administrators" to gain access to the dropdown menu. Once the build has been first created, a project build administrator can edit the build as desired.