Windows 10 child account missing from sign-in screen after being added to Microsoft Family

I searched for the resolution to the issue above and found nothing related to my specific issue. In order to help others that may find them selves in this same place, I am posting how I resolved the issue.

After a Windows 10 refresh, one of my child account no longer showed on the Sign-In Screen. I removed the account from MS Family Safety online, then removed the account off the PC and confirmed the account no longer was on the PC. The mandatory windows reboot, and again confirm the account was removed from Family & other users. 
Adding the child account back into Family Safety, I confirmed the account was added back in under Settings → Accounts → Family & other users. Confirmed that I could see the account in the registry, windows had a SID.

net user [child account name]

OR

net user

Confirming the account is registered on the PC.

Confirm we have a SID 

wmic useraccount where name='[Account Name]' get name,sid,status

Once I confirmed that windows was seeing the account and the child account appeared under Settings → Accounts → Family & other users, was enabled, and had permission to sign in, but it did not appear on the sign-in screen or under Switch user.

Resolution:

1. Open secpol.msc.
2. Under Local Policies → Security Options, enable Interactive logon: Don’t display last signed-in.
3. Sign out and use the resulting Other user prompt to sign in with the child’s Microsoft-account email address and password.
4. While signed in to the child account, open Settings → Accounts → Sign-in options.
5. Add or recreate the child account’s Windows Hello PIN.
6. Sign out and set Interactive logon: Don’t display last signed-in back to Disabled.
7. Restart the PC.

After the restart, the child account appeared normally on the sign-in screen.

The account had already been enabled, allowed, and assigned a valid Windows profile. Recreating the Windows Hello PIN was the step that restored its sign-in tile.

Full disclosure, Copilot assisted with troubleshooting, this is a high level review of the steps taken that resulted in the account showing up on the Sign-In screen.