EDIT: More context, my device was still locked after a reset. Solution below allows your data to be preserved, and should be the first thing tried before resetting the computer.
Couldn't find a solution anywhere for this myself. Since this is the latest thread on the topic I will post the solution that worked for me here.
- Restart device while holding shift to enter Windows Recovery Environment. Troubleshooting > Advanced Options > Open CMD. This is where you will need your recovery key.
- After CMD is open, type "regedit" and hit enter.
- Click "HKEY_LOCAL_MACHINE", then "File" in top left corner, then "Load Hive".
- A file explorer should appear. It should be "System32" as the folder already. If not, follow: This PC > (C:) Drive > Windows > System32
- Navigate to "Config" > "Software". Pop up box named "Keyname" should appear. Enter '1234' as keyname. Box will close after complete.
- Expand "HKEY_LOCAL_MACHINE" > expand folder "1234" > Microsoft > WindowsNT > CurrentVersion > PasswordLess > Device.
- Double click "DevicePasswordBuildVersion" from window beside file directory. Change value data from '2' to '0'.
- Restart computer by exiting the Recovery Environment.
- Should now have access to "Sign-In Options" on the sign in page. Choose "Sign-In with Microsoft Account" and use your account details.
- Everything should be back to normal, you will have to create a PIN again if you so choose, following the usual steps in settings.
Pretty ridiculous to have this option available without clearly informing the user of the ramifications, and the inability to unlock your device once found.