User login to a workstation locks a different user's AD account

Ok, here's a weird one. Just started happening yesterday (after updates were applied over the weekend?):

User A is assigned to workstation A (which is a Windows 10 workstation). When she leaves for lunch, User B logs onto her workstation to assist customers while User A is at lunch. When User A comes back from lunch and attempts to login to her workstation, she is getting notified that her account is locked out.

I check AD Users and Computers and find User B's account is locked but not User A. I advise User A to reboot the workstation and she can now login. I verified that she was logging in by entering her password for her own user ID - actually watched her enter her password under her User ID, but it is recording login attempts against User B's account.

This happened yesterday and again today. I have other workstations which users share, substituting for each other during lunch breaks but have not received any reports of this type from other users.

I've done a couple of preliminary Google searches but I'm not finding anything similar. My first thought is to delete User B's profile off the workstation since he's not the primary user on that workstation anyway. I'm hoping I don't have to also delete and rebuild User A's profile.

Anyone else seen anything like this and have any suggestions?