Microsoft had today pushed a new Windows 10 Mobile Build to insiders in Fast Ring. This build 15207 only has a single fix over last Build 15205. The fix is related to the Windows 10 Mobile privacy page that you may have seen after installing Build 15205.
Read the details of this single fix below,
We have added a privacy page to the Windows 10 Mobile OOBE and upgrade experiences that allows you to quickly and effectively make common privacy changes while setting up the device. However, Insiders have reported that their device would crash or reboot shortly after unlocking their device for the first time after the upgrade if their device did not have a password configured to unlock the device.
After updating to Build 15207, you will see this privacy page one more time – but should no longer experience a crash or reboot.