Time limit for active but idle sessions

Hello,

I setup the GPO to introduce RDP session time limits for disconnected sessions and time limits for active but idle sessions. The GPO is configured under Computer Configuration, and linked for the whole site and Authenticated Users.

It's successfully propagated and applied to all domain computers -- I see all relevant registry keys applied and gpresult shows no errors. However, already connected (prior to introducing this GPO) sessions don't seem to be terminated. Is this expected?

Thank you.