While it may be tempting to jump into the Android 11 Developer Previews, be warned that bugs are still abound. And if you’re using a Pixel 4 or 4 XL, a particularly nasty one can take out Face unlock.
Several reports have surfaced of Android 11 Developer Preview 3 (DP3) causing issues with Face unlock when users try to revert back to stable Android 10 builds. Specifically, when you get back to Android 10, Pixel 4 and 4 XL devices will be unable to set up Face unlock.
Every time you try to enroll a face, the phone will show a pop-up that says “Face enrollment didn’t work.”
I encountered this issue myself on my Pixel 4. I had updated to DP3 but encountered another bug that caused the phone to freeze up when the screen was off. I decided to go back to stable, but then Face unlock didn’t work. Ultimately, I went back to DP3, which fixed Face unlock but left me with a mostly unusable Pixel thanks to the other bug. Luckily I had a backup phone to use.
Ultimately, if you’re considering hopping on the Developer Preview train — which may be enticing with the new DP4 release — I’d advise holding off, especially if you don’t have a backup device. Google lists the new bug as a “user-facing issue” in the release notes for DP4. However, it’s not clear if DP4 fixes the problem.
If you’ve already tried out DP3 and gone back to stable Android and are stuck with the bug, there are a few things you can try. Reddit, Google support and XDA threads have all popped up about the issue and detail different possible solutions. Further, some users have reportedly had success getting a new phone through an RMA request.
Source: Android Police