@meganinja202 I don't know it feels like negotiations went something like "If you give us the source code for insert build number here we'll handle localization, deployment, and server maintenence. We can split the profit xx% to yy%. When they reached an agreement MS took the pre-compiled code, ripped out the existing login interface in favor of calling an external dependency. They didn't bother checking for any: exceptions that may need to be thrown when calling for external dependencies, known issues with that build of the installer, or issues that may occur when not installing the game in their ideal scenario.
That seems to me to be the most likely scenario. Though I haven't been able to get into the game in order to check the credits, and I sincerely doubt anyone is going to stand up and shout "integrating Xbox Live's identity verification tool without telling people when an issue occurred was my idea".