You are running a BETA. No one but Google forums will give you much if any support.
Put the phone back to factory condition and hope that clears it up to avoid a trip to the repair shop or maker.
I have a oneplus 6 and my lock button doesn't seem to be working, so i cant unlock or lock the phone and my only way of doing so is by connecting it to a power source or directly using my finger print, this also means my double press for camera, or long press for power menu doesn't work, on top of this, my off screen drawing gestures or my double tap to wake doesn't function even though it is enabled in the settings menu. What can i do apart from getting it showed to a technician as i have none nearby. Btw i have developer options enabled and am on android 9 beta.