This is not a bug. It is working as intended!
Active pause continues to simulate the plane flying but stops it from moving. Another example of this is when you are climbing and active pause, your airspeed will continue to drop and then when you unpause, you will instantly stall.
There are keybindings called ‘set pause on’ and ‘set pause off’ that you can assign to buttons in the settings. This will ‘properly pause’ the game.
Edit: See this wishlist item discussion