Session lock preventing sleep mode?

[MS]

Session lock works properly now on a laptop, nonetheless each time I close the lid - initiating sleep mode - with the session lock feature on, the display would shut down and the session lock is confirmed to kick in, but the fan in the machine keeps spinning long time and by the general appeal it seems to be constantly working.

[MS]

Still up, the session lock inhibits the sleep mode when laptop lid is shut. Which is, the session would lock, but the machine keeps running, even if simultaneously it is ordered to enter sleep mode on lid down. If to disable the session lock, on lid down the system goes to sleep as expected.