Is that different on the XBox version perhaps or windows store version?
Esc definitely pauses the game, same as using Set Pause On.
(Bind a key to Set Pause On and Set Pause Off, it’s the real pause, never use active pause)
However pause only pauses your plane and its systems. The world moves on. (At least with live weather/traftic/multi player).
Sim rate is also inconsistent, it affects your plane and fauna, but not cars, plane traffic. Sim rate does affect time progression, but not weather progression.
Set Pause On works for your plane at least. Most you’ll get is ATC getting impatient, as in telling you to expedite your climb/descent when resuming.