This 1704 build is flighting today to Preview RING 4 only. Ring 4 users please Report a Problem if you see any issues please with this build.

We have just posted this to the Xbox Forums (restricted access via Xbox Insider membership) and I wanted to share here.

If your console is in Instant-On mode and you have been selected to receive the update, it will download and install the update and reboot to standby.
• NOTE: Once the update is available to you, you can manually begin the update by launching the Guide and navigating to All Settings > System > Updates.
• If you have been selected to receive the update and your console hasn’t downloaded and installed the update by 1:00 AM PDT 4/29/2017, you will be prompted to do so at that time.

OS version released: rs2_release_xbox_1704.170426-1958
Available: 2:00PM PDT 4/28 (9:00PM GMT 28/4)

  • Miscellaneous fixes and improvements.

Source: Xbox One Insider Program - April 28th : New Preview Ring 4 1704 Build Available (1704.170426-1958) : xboxone