When I restart my phone and the lock button appears to allow me to enter my passcode, the button takes several presses before it works. Sometimes the screen flickers black or fades dark. I need to press the power button to make it appear again. The fingerprint scanner works without issue.

Is anyone else experiencing this? It creeps me out a bit that my OS has a unique issue. It took dozens of tries to keep the passcode screen open long enough to enter it this time.

On my P8Pro my screen hasn't flickered yet but I have to slide my screen several times to be able to unlock the device. I think this is related to a bug someone mentioned on the OS issues tracker where the bottom of the screen doesn't immediately function when the unlock menu is presented.
It isn't directly related to your issue but it might be caused by the same bug.

    FOSSOS
    This also seems to be happening on my 6a. Both the 6a and 8a are on the stable release channel. Where can I find the issue tracker?