Xbox One Insiders signed-up to the Alpha ring were expecting a new build on Saturday. Due to an issue, this build got delayed, and was then expected to be released late on Sunday.
Unfortunately, the Xbox team are continuing to see issues with this build that is causing Microsoft to hold the roll out of the build. As a result, Brad Rossetti of the Xbox Preview Program team, has announced that the build is now expected to release next week, on Wednesday.
Xbox One Insiders - No new 1805 build for Alpha users today given some issues. The team is working hard to release a new one ideally Wed with new features and lots of fixes.
— Brad Rossetti (@WorkWombatman) April 29, 2018
The good news is that, should the build release on Wednesday, it will be bringing new features, as well as "lots of fixes". What these new features will be included in the build are unknown at the moment.