What should I do if Windows 10 not locking on sleep?

My Windows 10 computer is not locking automatically when it goes to sleep. I have confirmed that the "Require sign-in when the PC wakes from sleep" setting is turned on in my power options, but when the screen turns off or the system sleeps, anyone can still move the mouse or press a key to get full access to my desktop without being prompted for a password. This is a major security concern, and I have already tried updating my graphics drivers and checking for any conflicting settings in the screensaver and lock screen menu without any success. I am looking for any other troubleshooting steps or potential fixes that could resolve this issue and make sure my PC properly locks itself every single time it enters sleep mode.