If you've been experiencing some hiccups with online matchmaking via Xbox Live, it's not just you. According to Microsoft's Xbox Live Service Status page, the company is currently investigating issues with matchmaking across the Xbox One, 360 and PC. From Microsoft:
Hey Xbox members, are you having trouble creating or joining your multiplayer sessions? Are you running into an issue with viewing notifications? We are aware of these issues and are working with our engineers to get this corrected ASAP! Thank you for your patience while we work. We'll post another update when more information becomes available.
You may experience problems with cloud storage, finding friends, Game DVR and editing your avatar, in addition to matchmaking woes. As Microsoft is aware of the issue, hopefully it will be resolved before too long. We'll update this post when everything is in the clear.