you say it goes to lock screen as soon as you press sleep, its possible something is waking it as soon as you sleep it, and it goes there. So yes, sleep isn't staying on, it might not come on at all. But command at least checks to see if something is waking it as soon as you sleep it.
you can try safe mode and see if it sleeps in there
- go to settings/update & security/recovery
- under advanced startup, click restart now button
- this restarts PC in a blue menu
- choose troubleshoot
- choose advanced
- choose startup options
- click the restart button
- choose a safe mode (it doesn't matter which) by using number associated with it.
- Pc will restart and load safe mode
or you can try a clean boot which removes all programs apart from windows from the start process (temporily)
Try a clean boot and see if it changes anything - make sure to read instructions and make sure NOT to disable any microsoft services or windows won't load right -
https://support.microsoft.com/en-au/help/929135/how-to-perform-a-clean-boot-in-windows
if clean boot fixes it, it shows its likely a startup program. You should, over a number of startups. restart the programs you stopped to isolate the one that is to blame.