Command + Tab does not work consistently on MacOS
Open Terminal and type
killall Dock
Hit return.
Your Dock will disappear for a second and then reappear but open apps will not be affected.
Try Cmd+Tab now.
On MacOS you would get best switching experience if you DO NOT MINIMIZE your windows.
Command + Tab : to switch to windows that are not minimized
Command + Tab followed by Option : to switch to a minimized window
When I asked this question, I was a newbie MacOS user with years of Windows experience.
Now, it feels like MacOS design is optimized towards leaving your windows open (irony)