Control yaw during CIRCLE mode

Hello folks,

I am little confused about controlling yaw during circle mode.
The documentation mentions that “The pilot can control the yaw of the copter, but the autopilot will not retake control of the yaw until circle mode is re-engaged.”. ( it is meaning users cannot control yaw. Am I right?
Also, based on previous post (Unable to control yaw in CIRCLE mode), users cannot control yaw.
But, I can still control yaw on SITL.
After I turns on the circle mode, when I change the yaw value such as “rc 4 1000”. It increases rotation speed as well as making the drone unstable status.
is it normal or a bug?

Thanks in advance!