Big YAW after transitioning

I’ve been trying to fly a plank wing except every time I try to fly it in FBWA it yaws way off out of control. I checked the logs and i noticed that when entering FBWA that ATT.desyaw plunges immediately to zero while ATT.yaw stays the same value, then I think it sees these two huge differences in desired yaw vs actual yaw and thus tries to correct itself but it does it too fast and causes it to lose control.

Is this what’s actually happening?

here’s a graphical representation of the change in desired yaw, ATT.yaw isn’t changing because i did it on my desk with motors off: