You're still flying with SAS yaw, try turning it off.
I just tried out with SAS Yaw off and in a hover it can lead to some rapid yaw movement without the governors kicking in. Regarding sideslip with SAS Yaw off in forward flight the sideslip does not appear to be happening from where I'm sitting but mostly I am impressed with the Harrier. BTW with all of SAS off it is very difficult to control. 4 7 18 AV8B yaw SAS off.trk