I am observing this same issue.
My teslafi.com shows me my Idle has been stuck for loooong time "Days" - I just increase the time to try to make car sleep from 15 minutes up to 45 minutes to see if it finally goes to sleep.
You can check
TeslaFi.com Tesla Model S 3 X Y Data Logger for live data and see if it ends up going to sleep. I am still trying to figure this out myself. It was working fine before the update