Through the official Xbox support account, it has been announced that the service is currently presenting some problems related to navigation, login, content purchase, and code redemption.
From the Twitter profile, they have announced that they are already working on solving the problem and hope to have it solved soon. If when you enter the store you experience this type of problem, they are localized and it is not a problem with your connection or with your Xbox Live account.
Xbox Live login issues
As the problem mainly affects the login, those users who want to start playing and were not logged in before, cannot access it.
You may not be able to sign in to your Xbox profile, you might get disconnected, or have other related issues. Features that require a login, such as most games, apps, and social activity, will not be available.