Mac OS Sierra 10.12.1 Dock behaviour and command tab issue I've got a brand new computer which I bought last week. I've noticed that sometimes when I cycle programmes using command and tab, some of the icons don't appear, even though the programme is open. The only way I can get to them is to click the icon on the dock or find the window manually.

I've also noticed that quite often when I quit a programme it remains as if it were open in the dock, even though it has been quit.

To fix it I can run killall Dock in terminal, but it then later happens again. Not ideal.

Can anyone else report something similar? I'm trying to diagnose if its an issue with the computer or Sierra; I don't want to have to send it back but shouldn't be having problems this early on. I even did a clean reinstall this morning and the problem still persists.
Yes. I have a mid 2015 MBP which I have upgraded to Sierra from Mavericks and before that all the way back to Lion.

I find that Cmd-Tab frequently (more often than not) fails to tab to the correct window, stopping 'one short' which suggests that the list of icons displayed when Cmd Tabbing is different from the internal list of programs that it cycles through for some reason.

I also recently had a problem (for the first time) where Terminal windows failed to show in the task switcher at all until I restarted the OS.