Insiders are reporting that with build 15245 for Windows 10 Mobile, the fingerprint readers on the HP Elite x3 and Alcatel IDOL 4 Pro are no longer functioning while the screen is off, rendering Windows Hello useless unless you power on the screen first.

As with most phones, fingerprint reader support in Windows 10 Mobile works whether the screen is on or off, allowing you to login via Windows Hello without having to power on the screen first. But in build 15245, it appears this function is broken, requiring you to power on the display before the fingerprint reader becomes active.

This is a pretty major bug, and our readers are reporting this issue is apparent on both the Elite x3 and IDOL 4 Pro, the only two Windows phones that rock a fingerprint reader on Windows 10 Mobile. Oops.

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What's more, this bug isn't listed as a known issue on the Windows Blog. Perhaps that's because Microsoft has decided to stop providing a list of known issues now we're headed towards the end of Redstone 3 development, or maybe it's because Microsoft isn't testing their internal Mobile builds much anymore.

Regardless, are you hitting this bug? If so, we suggest you file feedback via the Windows Feedback app and let Microsoft know. The sooner this bug gets mended, the sooner Windows phone fingerprint readers will become useful again.