Windows 10 Mobile Insider Preview build 15222 is now available in the Fast ring

Three weeks ago, Microsoft released Windows 10 Mobile Insider Preview build 15215 to phones in the Fast ring. It was the newest of several builds to emerge from the 'feature2' development branch, while PCs have continued to receive previews from the more advanced Redstone 3 branch which will eventually become the Fall Creators Update later this year.

Microsoft was planning to push build 15220 to Mobile Insiders last week, but an issue led to build 16212 accidentally rolling out to phones on all Insider rings, including some versions of the build designed for Xbox and IoT devices. Now, the wait for a new build is over; alongside build 16215 for PCs, Microsoft has begun rolling out Windows 10 Mobile build 15222 to phones in the Fast ring.

Unfortunately, as with other feature2 builds, there are no new features in this latest build. Instead, Microsoft is continuing to focus on bug fixes and other improvements:

This build also includes all the improvements from KB4016871 and KB4020102.

The copyright date is correctly showing 2017 now under Settings > System > About.

We fixed an issue where WhatsApp would not launch after updating to the latest Mobile builds.

We fixed an issue with using the Japanese 12 Key soft keyboard where the “right arrow” key did not input a space

We fixed an issue with the Bulgarian keyboard localization for the HP Lap Dock in Continuum.

We have further improved the reliability of notifications for apps with a paired Bluetooth device, such as Fitbit.

Improved the Time & Language settings page UX for Speech and Keyboard language downloads. Previously, the status would show “Downloading” for speech and “Installing” for keyboard. Unless, the user tapped on the language or navigated to the Update & Security settings page, there was no indication that a restart is required to complete the installation. Now when the update reaches the reboot pending state, a “Restart Required” is displayed under the language.

We fixed several enterprise device management issues.

We fixed an issue where notifications and Cortana’s cross-devices settings on your device were not being mirrored to your PC.

There's a single known issue in this latest build too: